System and method for orthopedic measurement and alignment

ABSTRACT

At least one embodiment is directed to a system for distracting bones of a muscular-skeletal system. The dynamic distractor ( 100 ) comprises at least one sensor ( 108, 110 ), a handle ( 112, 804 ), a lift mechanism ( 302 ), and one or more alignment aids ( 502, 802 ). The position and measurement sensors ( 108, 110 ) are in communication with the processing unit ( 406 ) to display, process, and store measured data. The process of distraction separates two components such as bones of the muscular-skeletal system. Dynamic distractor ( 100 ) can aid in the alignment of the skeletal system and to verify that alignment is correct. A surface or feature on a handle of dynamic distractor ( 100 ) has a relational position to one of the surfaces being distracted. The surface has an optimal alignment to a mechanical axis. An alignment aid ( 502, 802 ) is coupled to the surface or feature to measure alignment to the mechanical axis.

CROSS-REFERENCE

This application claims the priority benefits of U.S. Provisional PatentApplication No. 61/211,023 filed on Mar. 26, 2009, the entire contentsof which are hereby incorporated by reference. This application furtherclaims the priority benefit of U.S. provisional patent applications No.61/221,761, 61/221,767, 61/221,779, 61/221,788, 61/221,793, 61/221,801,61/221,808, 61/221,817, 61/221,867, 61/221,874, 61/221,879, 61/221,881,61/221,886, 61/221,889, 61/221,894, 61/221,901, 61/221,909, 61/221,916,61/221,923, and 61/221,929 all filed 30 Jun. 2009. The disclosures ofwhich are incorporated herein by reference in its entirety.

FIELD

The disclosure relates in general to orthopedics, and particularlythough not exclusively, is related to a device and method to facilitateorthopedic surgery.

BACKGROUND

The skeletal system is a balanced support framework subject to variationand degradation. Changes in the skeletal system can occur due toenvironmental factors, degeneration, and aging. An orthopedic joint ofthe skeletal system typically comprises two or more bones that move inrelation to one another. Movement is enabled by muscle tissue andtendons attached to the skeletal system of the joint. Ligaments hold andstabilize the one or more joint bones positionally. Cartilage is a wearsurface that prevents bone-to-bone contact, distributes load, and lowersfriction. The spinal column is comprised of vertebrae, discs, ligaments,and muscles that stabilize the vertebral column and protects the spinalnerves.

There has been substantial growth in the repairing of the human skeletalsystem as orthopedic joint implant technology has evolved. In general,improvements to orthopedic implant joints have been based on empiricaldata that is sporadically gathered from real patients. Similarly, themajority of implant surgeries are being performed with tools that havenot changed substantially in decades but have been refined over time. Ingeneral, the orthopedic implant procedure has been standardized to meetthe needs of the general population. Adjustments due to individualskeletal variations rely on the skill of the surgeon to adjust theprocess for the exact circumstance. At issue is that there is little orno data during an orthopedic surgery, post-operatively, and long termthat provides feedback to the orthopedic manufacturers and surgeonsabout the implant status.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a top view of a dynamic distractor in accordance with anexemplary embodiment;

FIG. 2 is a side view of a dynamic distractor having a minimum height inaccordance with an exemplary embodiment;

FIG. 3 is a view of a dynamic distractor opened for distracting twosurfaces from each other in accordance with an exemplary embodiment;

FIG. 4 is an anterior view of a dynamic distractor placed in a kneejoint in accordance with an exemplary embodiment;

FIG. 5 is a lateral view of dynamic distractor in a knee jointpositioned in flexion in accordance with an exemplary embodiment;

FIG. 6 is a lateral view of a dynamic distractor in a knee joint coupledto a cutting block in accordance with an exemplary embodiment;

FIG. 7 is an anterior view of a cutting block coupled to dynamicdistractor in accordance with an exemplary embodiment;

FIG. 8 is an illustration of dynamic distractor including alignment inaccordance with an exemplary embodiment;

FIG. 9 is a side view of a leg in extension with a dynamic distractor inthe knee joint region in accordance with an exemplary embodiment;

FIG. 10 is a top view of a leg in extension with a dynamic distractor inthe knee joint area in accordance with an exemplary embodiment;

FIG. 11 is an illustration of a system for measuring one or moreparameters of a biological life form in accordance with an exemplaryembodiment;

FIG. 12 depicts an exemplary diagrammatic representation of a machine inthe form of a computer system within which a set of instructions, whenexecuted, may cause the machine to perform any one or more of themethodologies discussed above;

FIG. 13 is an illustration of a communication network for measurementand reporting in accordance with an exemplary embodiment;

FIG. 14 is an exemplary method for distracting surfaces of themuscular-skeletal system in accordance with an exemplary embodiment;

FIG. 15 is an exemplary method for distracting surfaces of themuscular-skeletal system in extension and in flexion in accordance withan exemplary embodiment;

FIG. 16 is an exemplary method for distracting surfaces of themuscular-skeletal system in extension and in flexion in accordance withan exemplary embodiment;

FIG. 17 is an exemplary method for distracting surfaces of a knee jointin extension and in flexion in accordance with an exemplary embodiment;

FIG. 18 is an exemplary method to place the muscular-skeletal system ina fixed position for bone shaping in accordance with an exemplaryembodiment;

FIG. 19 is an exemplary method of measuring the muscular-skeletal systemin accordance with an exemplary embodiment;

FIG. 20 is an exemplary method of a disposable orthopedic system inaccordance with an exemplary embodiment; and

FIG. 21 is an exemplary method of a disposable orthopedic system inaccordance with an exemplary embodiment.

DETAILED DESCRIPTION

The following description of exemplary embodiment(s) is merelyillustrative in nature and is in no way intended to limit the invention,its application, or uses.

Processes, techniques, apparatus, and materials as known by one ofordinary skill in the art may not be discussed in detail but areintended to be part of the enabling description where appropriate. Forexample specific computer code may not be listed for achieving each ofthe steps discussed, however one of ordinary skill would be able,without undo experimentation, to write such code given the enablingdisclosure herein. Such code is intended to fall within the scope of atleast one exemplary embodiment.

Additionally, the sizes of structures used in exemplary embodiments arenot limited by any discussion herein (e.g., the sizes of structures canbe macro (centimeter, meter, and size), micro (micrometer), nanometersize and smaller).

Notice that similar reference numerals and letters refer to similaritems in the following figures, and thus once an item is defined in onefigure, it may not be discussed or further defined in the followingfigures.

In all of the examples illustrated and discussed herein, any specificvalues, should be interpreted to be illustrative only and non-limiting.Thus, other examples of the exemplary embodiments could have differentvalues.

In general, successful orthopedic surgery including the implantation ofan orthopedic device into the muscular-skeletal system depends onmultiple factors. One factor is that the surgeon strives to maintainadequate alignment of the extremity or implanted device to the ideal. Asecond factor is proper seating of an implant for stability. A thirdfactor is loading on the skeletal system or replacement implant. Afourth factor is alignment of implanted components in relation to oneanother. A fifth factor is balance of loading over a range motion.

By way of a device herein contemplated, the surgeon receives measureddata during surgery and post operatively on the factors listed above. Asone example, accurate measurements can be made during orthopedic surgeryto determine if bones or an implant are optimally balanced and aligned.This can reduce operating time and surgical stress for both the surgeonand patient. The data generated by direct measurement can be furtherprocessed to assess long-term integrity based on maintaining surgicalparameters within predetermined ranges. The measured data in conjunctionwith patient information can lead to improved design and materials.

FIG. 1 is a top view of a dynamic distractor 100 in accordance with anexemplary embodiment. Dynamic distractor 100 is also known as a dynamicspacer block. Dynamic distractor 100 is a sensored device that is usedduring surgery of a muscular-skeletal system. Dynamic distractor 100 canbe used in conjunction with other tools common to orthopedic surgery aswill be disclosed in more detail hereinbelow. In at least one exemplaryembodiment, the system is used during orthopedic joint surgery and morespecifically during implantation of an artificial joint. The system usesone or more sensors intra-operatively to define implant loading,positioning, achieve appropriate implant orientation, balance, and limbalignment. In particular, dynamic distractor combines the ability toalign and measure one or more other parameters (e.g. load, blood flow,distance, etc. . . . ) that provides quantitative data to a surgeon thatallows the orthopedic surgery to be measured and adjusted withinpredetermined values or ranges based on the measured data and a databaseof other similar procedures. The system is designed broadly for use onthe skeletal system including but not limited to the spinal column,knee, hip, ankle, shoulder, wrist, articulating, and non-articulatingstructures.

Dynamic distractor 100 comprises an upper support structure and a lowersupport structure. An active or dynamic spacer portion 120 of dynamicspacer block comprises the upper and lower support structures. A liftmechanism (not shown) couples to an interior surface of upper supportstructure and an interior surface of the lower support structure. Ahandle 112 couples to the lift mechanism. In one embodiment, handle 112is operatively coupled to the lift mechanism to change a gap of thespacer block. Handle 112 can also be used to guide dynamic distractor100 between regions of the muscular-skeletal system. In general, theupper support structure has a superior surface 102 that interfaces witha surface of the muscular-skeletal system. Similarly, the lower supportstructure has an inferior surface that interfaces with a surface of themuscular-skeletal system.

In one embodiment, handle 112 can be rotated to adjust the liftmechanism to increase or decrease a gap between the superior andinferior surfaces of the active spacer block thereby modifying theheight or thickness of dynamic distractor 100. In a non-limiting exampleto illustrate a disposable aspect, superior surface 102, the inferiorsurface, or both surfaces include at least one cavity or recess forhousing at least one sensor module. The sensor module includes at leastone sensor for measuring a parameter of the muscular-skeletal system.For example, the sensor can measure a force or pressure. As will bedisclosed hereinbelow, the sensor can be disabled so it cannot be reusedand disposed of after the procedure has been performed. In a furtherexample, dynamic distractor 100 can be placed between two or more bonesurfaces such that the superior surface 102 and the inferior surfacecontact surfaces of the muscular-skeletal system related to a joint. Inone embodiment, the sensor is coupled to a surface of themuscular-skeletal system for measuring a parameter when positionedbetween surfaces. Handle 112 can be rotated to different gap heightsallowing pressure measurements at the different gap heights to generatedata of gap versus pressure.

Handle 112 further includes an opening 114, a decoupling mechanism 118,and a display 116. Opening 114 is used to receive additional componentsof the system that will be described in more detail hereinbelow.Decoupling mechanism 118 allows removal of the handle during parts of asurgery to allow access to the muscular-skeletal system. Decouplingmechanism 118 couples to a locking mechanism that locks handle 112 to ashaft of the lift mechanism. Decoupling mechanism 118 releases thelocking mechanism thereby allowing handle 112 to be removed from dynamicdistractor 100. In one embodiment, the locking mechanism is a pin orball that fits into a corresponding feature 122 on the shaft of the liftmechanism. Decoupling mechanism 118 releases or frees the pin or ballfrom feature 1122 thereby allowing removal of handle 112. Alternatively,decoupling mechanism 118 can be a hinge or joint that allows handle 112to move in a direction that allows greater access by the surgeon to anarea where the spacer block portion of dynamic distractor 100 has beenplaced. The display 116 on handle 112 can provide a readout of the gapbetween the superior surface 102 and the inferior surface as handle 112is rotated to adjust spacing.

In a non-limiting example, dynamic distractor 100 is adapted for use inartificial knee implant surgery. It should be noted that dynamicdistractor 100 can be similarly adapted for other orthopedic surgerywhere both distraction and parameter measurement is beneficial. A kneeimplant is used merely as an example to illustrate how dynamicdistractor 100 can be used in a surgical environment. In at least oneexemplary embodiment, the superior surface 102 of dynamic distractor 100includes a recess or cavity 104 and a second recess or cavity 106. Inone embodiment, a sensor 108 and a sensor 110 are pre-sterilized in oneor more packages. The packaging is opened prior to or during surgerywithin the surgical zone to maintain sterility. Sensors 108 and sensor110 are shown respectively placed in cavities 104 and 106 for measuringa parameter that aids in the surgical procedure. In the knee example,sensors 108 and 110 include pressure sensors such as strain gauges,mechanical-electrical-machined (mems) sensors, diaphragm structures,mechanical sensors, or other pressure measuring devices. In oneembodiment, a major exposed surface of sensors 108 and 110 is in contactwith the muscular-skeletal system after insertion. Alternatively, one ormore layers of material or portions of the muscular-skeletal system canbe between sensors 108 and 110 such that the parameter can be measuredor transferred through the intervening layers. A force or pressureapplied to the exposed surfaces is measured by sensors 108 and 110 whilethe gap of the dynamic distractor is adjusted. Alternatively, the liftmechanism in conjunction with sensors 108 and 110 can be set to apredetermined pressure. The lift mechanism gap will increase until thepredetermine pressure is reached. Thus, identifying a gap height orthickness of dynamic distractor 100 to achieve the predeterminedpressure.

In at least one exemplary embodiment, sensors 108 and 110 are disposabledevices. After measurements have been taken, sensors 108 and 110 can beremoved and disposed of in an appropriate manner. Alternatively, thesensors 108 and 110 can be permanent or an integral part of the superiorsurface of dynamic distractor 100. The housing can be designed to bereused and to withstand a sterilization process after each use. The mainbody of dynamic distractor 100 as well as sensors 108 and 110 arecleaned and sterilized before each surgical usage.

Dynamic distractor 100 in a zero gap (or closed condition) is less than8 millimeters thick for the knee application and can expand using thelift mechanism to greater than 25 millimeters. This range is sufficientfor the majority of artificial knee implant surgeries being performed.The spacer portion 120 of dynamic distractor 100 contains the superiorsurface 102 and the inferior surface that articulates to at least twobone ends of the muscular-skeletal system. In the knee example, thedynamic distractor 100 is placed between the distal end of the femur andthe proximal end of the tibia. As mentioned previously sensors 108 and110 are in a housing. In one embodiment, the housing includes sensorelements to define the loads on the medial and lateral compartments. Thesensored elements can comprise load displacement sensors,accelerometers, GPS locators, telemetry, power management circuitry, apower source and an ASIC.

As disclosed above, the spacer portion 120 of dynamic distractor 100 isplaced between the femur and tibia in extension. The dynamic distractor100 is configured with no gap (e.g. minimum height or thickness) orhaving a gap that can be inserted and removed without tissue damage. Ingeneral, the gap can be increased by rotating handle 112 after insertionsuch that the inferior surface of dynamic distractor 100 contacts aprepared surface of a proximal end of a tibia and the superior surfacecontacts the prepared distal end of the femur. In general, the femoraland tibial cuts in extension are made parallel to one another.Similarly, the femoral cut in flexion is made parallel to the preparedend of the tibia. The gap is measured to determine a combined thicknessof the implants with the leg in extension. The prepared ends of thetibia and femur can be checked for alignment with the mechanical axis atthis time as will be disclosed in detail below.

Typically, the surgeon selects the artificial components based on thecross-sectional size of the prepared bones. The variable component ofthe implant surgery is the final insert. The final insert has one ormore bearing surfaces for interfacing with a femoral implant. In oneembodiment, the measured gap height created by dynamic distractor 100 isused to define an insert thickness or height. The thickness of a finalinsert can change during surgery as further bone cuts or tissuetensioning occurs. Dynamic distractor 100 can be used during surgery tomeasure loading and gap height after each bone modification or after anorthopedic component has been implanted.

Dynamic distractor 100 can also be used to obtain an optimal balance.Balance is related to the measured loading between two or more areas.The measured values can than be adjusted to a predetermined relationshipand within a predetermined value range. In the knee example, balance isassociated with the differential pressure applied by each condyle on thebearing surfaces of the implant. Ideally, a predetermined surface areaof the femoral implant condyle contacts the bearing surface todistribute the load and minimize wear. In a non-limiting example, apredetermined relationship between measured values by sensors 108 and110 of dynamic distractor 100 is maintained after implantation of theartificial components. In one embodiment, the balance of the knee ismaintained by having the measured load in each compartment approximatelyequal. A method to balance the loading of the compartments is throughligament release on the side having the larger loading value. Ligamentrelease reduces loading primarily on the adjacent compartment. Theloading can be read off a display on dynamic distractor 100 allowing thesurgeon to view the change in loading and the differential value witheach release. The lift mechanism provides sufficient room between thesuperior and inferior surfaces of dynamic distractor 100 for a surgeonto perform a release procedure without removing the device. A nextgreater thickness of an insert can be selected should the absoluteloading value on each condyle fall outside the predetermined range dueto the soft tissue release. Handle 112 can be rotated to increase thegap height to the next larger insert value to ensure the measuredloading falls within the predetermined range and the differentialloading falls within a predetermined range (after the soft tissuerelease).

The loading and balance of an implanted joint should be maintainedwithin the predetermined values throughout the range of motion. In atleast one exemplary embodiment, measurements are taken when the tibia isat a ninety-degree angle to the femur. Handle 112 is used to positionthe spacer block portion of distractor 100 between the femur and thetibia. The inferior surface of dynamic distractor 100 is in contact withthe prepared surface of the tibia. In one embodiment, the superiorsurface 102 is in contact with the remaining portion of the condyles ofthe femur. Thus, the condyle surfaces of the femur are in contact withsensors 108 and 110 on the superior surface of dynamic distractor 100.In the example, a gap height of dynamic distractor 100 is reduced toaccommodate the condyles that remain on the distal end of the femur inflexion. The gap height of dynamic distractor 100 can then be adjustedto a height corresponding to the gap height in extension less thethickness of the femoral implant whereby the leg in flexion is similarto the leg in extension.

The loading on sensors 108 and 110 with the leg in flexion can bemeasured. The measurement is of value if the condyles are not damaged ordegraded. In one embodiment, soft tissue release is used to adjust thebalance between compartments with the leg in flexion. The soft tissuerelease can also be performed later in the procedure after the femoralimplant has been implanted. Similar to the leg in extension, soft tissuerelease is performed to reduce the tension on the side having the highercompartment reading with dynamic distractor 100 in place. After softtissue release, the readings in each compartment should be within apredetermined differential range. The distal end of the femur can thenbe prepared for receiving the femoral implant, which removes theremaining portion of the condyles. As disclosed, the surface of thefemur is prepared to be parallel to the prepared tibial surface inflexion. This can be achieved by specific ligament releases in flexion,and/or rotation of the femoral implant to achieve a parallel levelsbetween the posterior femoral condyles and proximal tibia. A femoralsizer can be attached to the distractor to allow sizing of the femur,coupled with rotation of the femur. This allows dynamic rotation toobtain equally balanced flexion compartments.

In a non-limiting example, the femoral implant component can betemporarily attached to the distal end of the femur. Measurements can betaken throughout the entire three-dimensional range of motion usingdynamic distractor 100 to ensure that the implanted knee operatessimilarly in all positions. A gap provided by dynamic distractor 100would be adjusted to a combined thickness of the final insert thicknessand the tibial implant thickness. Dynamic distractor 100 canincrementally increase or decrease the gap to allow the surgeon todetermine how different insert thicknesses affect load and balancemeasurements. In one embodiment, accelerometers are used to provideposition and relational positioning information. The data can be storedin memory for later use or displayed to provide instant feedback to thesurgeon on the implant status. Further adjustments to load and balancecan be made with dynamic distractor in place if desired over differentpositions within the range of motion. Although one implant sequence isdisclosed, it is well known that surgeons have different approaches,methodologies and procedure sequences. The use of dynamic distractor 100would be applied similarly to distract and measure in differentrelational positions with the device in place. Furthermore, the devicecan be used or modified for use on different parts of the anatomy of themuscular-skeletal system.

FIG. 2 is a side view of dynamic distractor 100 having a minimum heightin accordance with an exemplary embodiment. Dynamic distractor comprisesan upper support structure 202 having superior surface 102 and a lowersupport structure 204 having an inferior surface 206. In the example,upper support structure 202, the lift mechanism, and lower supportstructure 204 supports loading typical for a joint of themuscular-skeletal system. Upper and lower support structures 202 and 204comprise a rigid and load bearing materials such as metals, compositematerials, and plastics that will not flex under loading. In oneembodiment, stainless steel is used in the manufacture of the liftmechanism and upper and lower support structures 204 and 202.

Dynamic distractor 100 is used to distract surfaces of themuscular-skeletal system. Dynamic distractor 100 can be used in aninvasive procedure such as orthopedic surgery. In the non-limitingexample, dynamic distractor 100 can distract surfaces of themuscular-skeletal system in a range of approximately 8 millimeters to 25millimeters. The support surfaces of dynamic distractor 100 do not flexunder loading of the muscular-skeletal system. In one embodiment,dynamic distractor 100 has a minimum height or thickness between supportsurfaces of less than 8 millimeters. In at least one application, aspace between support structures 202 and 204 is provided when dynamicdistractor 100 is opened to a height greater than the minimum height.The space between support structures 202 and 204 when opened allows asurgeon to perform soft tissue release with the device in place.

A cavity 104 is illustrated in superior surface 102 of upper supportstructure 202. The cavity 104 is shaped similarly to a housing 210 ofsensor 108. Housing 210 is placed within cavity 108 for measuring acompressive force applied across superior surface 102 and inferiorsurface 206. In the knee example, a condyle (implanted or natural)couples to an exposed surface of sensor 108. A pressure or force appliedto sensor 108 is measured and displayed by dynamic distractor 100.Sensor 110 is shown placed in its corresponding cavity in superiorsurface 102. In one embodiment, the exposed surfaces of sensors 108 and110 are approximately planar to the superior surface 102. The exposedsurface of sensor 108 and 110 can be flat or contoured. Sensors 108 and110 can be removed from upper support structure 202 and disposed afterthe surgery has been performed. In one embodiment, a push rod is exposedin the interior surface of upper support structure 202 that when pressedcan apply a force to housing 210 that removes sensor 108 from cavity 208

In one embodiment, housing 210 is formed of a plastic material. Thesensor and electronic circuitry is fitted in housing 210. The electroniccircuitry comprises one or more sensors 220, one or more accelerometers222, an ASIC integrated circuit 224, a power source 226, powermanagement circuitry 228, GPS circuitry 230, and telemetry 232. Thepower source 226 can be a battery or other temporary power source thatis coupled to the electronic circuitry prior to surgery. The powersource 226 has sufficient power to enable the circuitry for a period oftime that will cover the vast majority of surgeries. The powermanagement circuitry 228 works in conjunction with the power source tomaximize the life of the power source by disabling system componentswhen they are not being used. In general, an ASIC circuit controls andcoordinates when sensing occurs, can store data to memory, and cantransmit data in real time or collect and send data at a moreappropriate time to a remote system for further processing. The ASICincludes multiple ports that couple to one or more sensors 220. The ASICcouples, to at least one sensor 220, at least one accelerometer 222, GPS232, and telemetry circuitry 232. The ASIC 222 can include theintegration of telemetry circuitry 232, power management circuitry 228,GPS circuitry 230, memory, and sensors 220 to further reduce the formfactor of the sensing system. In the example, the at least one sensor220 is a pressure sensor that is coupled to the exposed surface of thehousing. The pressure sensor converts the pressure to an electricalsignal that is received by the ASIC. The at least one accelerometer 222and GPS 232 provides positioning information at the time of sensing.Telemetry circuitry 232 communicates through a wired or wireless path.In one embodiment, the data is sent to a remote processing unit that canprocess and display information for use by the surgeon or medical staff.One or more displays 234 can be placed on dynamic distractor 100 tosimplify viewing of a pressure or force measured by sensors 108 and 110thereby allowing real time loading and balance differential to be seenat a glance. The information can be stored in memory on the sensor ortransmitted to a database for long-term storage and processing.

In a zero gap or minimum height condition, the lift mechanism isenclosed within the device. An opening 212 exposes a threaded rod 216that is a component of the lift mechanism. The exposed end portion ofthreaded rod 216 is shaped for receiving handle 112. For example, aproximal end 214 of handle 212 is shown having a hexagonal opening thatoperatively couples to a hexagonal shaped end of threaded rod 216. Thesurfaces of the hexagonal surface mate with the surfaces of the threadedrod for distributing the torque required to rotate threaded rod 216 whenincreasing a gap between superior surface 102 and inferior surface 206to distract surfaces of the muscular-skeletal system. Distributing thetorque over a large surface area prevents stripping of either thehexagonal shaped opening of handle 212 or the hexagonal shaped exposedend of threaded rod 216 when the device is under load. In oneembodiment, a release and locking mechanism fastens handle 112 tothreaded rod 216. Pressing or sliding unlocking button 218 releases thelocking mechanism to allow removal of handle 112.

FIG. 3 is a view of dynamic distractor 100 opened for distracting twosurfaces of the muscular-skeletal system in accordance with an exemplaryembodiment. A lift mechanism 302 comprises a scissor mechanism 304 forraising and lowering upper support structure 202 and lower supportstructure 204. In one embodiment, scissor mechanism 304 comprises morethan one support structure each having a pivot. Scissor mechanism 304 isoperatively coupled to an interior surface of upper support structure202 and an interior surface of lower support structure 204. Thestructural beams are pinned to allow pivoting around the axis ofattachment. The remaining beam-ends rest on the interior surfaces ofeither the upper and lower support structures 202 and 204. The beam-endsnot fastened to the interior surfaces support upper and lower supportstructures 202 and 204 under load. Threaded rod 212 is operativelycoupled between the beam-ends of scissor mechanism 304 corresponding tolower support structure 204. Rotating rod 212 can increase or decreasedistance between beam ends of the scissor mechanism 204.

A rod 306 can be coupled to opening 114 of handle 112. The rod 306 canbe used to reduce the torque needed to rotate threaded rod 212 in eitherdirection under load. Increasing a distance between beam-ends of scissormechanism 304 reduces the gap between superior surface 102 and inferiorsurface 206 as the two or more beams pivot around a centrally locatedaxis. Conversely, decreasing a distance between beam-ends of scissormechanism 304 increases the gap between superior surface 102 andinferior surface 206.

FIG. 4 is an anterior view of a dynamic distractor 100 placed in a kneejoint in accordance with an exemplary embodiment. In the non-limitingexample, a distal end of a femur 102 is shown having a femoral implant.The femoral implant has artificial condyles that contact sensors 108 and110. The proximal end of a tibia 404 has been initially shaped forreceiving a tibial implant. As is well known by one skilled in the art,a complete knee implant comprises the tibial implant, the femoralimplant, and an insert that includes bearing surfaces that mate with theartificial condyle surfaces of the femoral implant. In one embodiment,dynamic distractor (100) includes an adjustable handle 112 that aids inthe insertion of the spacer portion into a joint region of themuscular-skeletal system. For example, the spacer portion of dynamicdistractor 100 is inserted into the knee joint using handle 112 but thenrotated away from the patellar tendon, collapsed into the trail, orremoved to allow the reduction of the patella to depict loads on theinstrument. The thickness or height of the three components iscontemplated for the bone surface preparation when using dynamicdistractor 100. In one embodiment, the combined thickness of the femoralimplant, final insert, and tibial implant is approximately 20millimeters thick. Adjustments to the prepared bone surfaces andthickness of the insert are made during surgery using data provided bydynamic distractor 100 to ensure correct loading, balance, andalignment.

Sensors 108 and 110 include circuitry for communication with aprocessing unit 406. In one embodiment, data is sent wirelessly using aradio frequency communication standard such as Bluetooth, UWB, orZigbee. The data can be encrypted to securely transmit the patientinformation and maintain patient privacy. In one embodiment, externalprocessing unit 406 is in a notebook computer, personal computer, orcustom equipment. For illustration purposes, external processing unit406 is shown in a notebook computer that includes software and a GUIdesigned for the surgical application. The notebook computer has adisplay 408 that can be used by the medical staff during the operationto display real time measurement from dynamic distractor 100. Thenotebook computer is typically placed outside the surgical zone butwithin viewing range of the surgeon.

A substantial benefit of dynamic distractor 100 is in performing softtissue release both in extension and in flexion. In extension, dynamicdistractor 100 can be set to a height corresponding to an insert size.In one embodiment, manufacturers of an implantable joint will providespecifications for load, balance, and alignment once sufficient clinicaldata has been generated. The surgeon can also manipulate the leg tosubjectively gauge the loading on the joint. The surgeon can adjustdynamic distractor 100 to increase or decrease the height or gapcorresponding to a different thickness insert size until a desiredloading is achieved. A substantial imbalance corresponds to adifferential loading measured by sensors 108 and 110 outside apredetermined range. The loading measured by sensors 108 and 110 shouldbe approximately equal in each compartment. The data provided by sensors108 and 110 can be used to provide a solution to the surgeon. Forexample, data from sensors 108 and 110 is sent wirelessly to processingunit 406. The data indicates a substantial differential pressure betweenmeasurements from sensors 108 and 110 (e.g. imbalance). In oneembodiment, the data can be processed and displayed on display 408 withsuggestions for the removal of material from the tibial surface toreduce the differential reading. The suggestion can include wherematerial should be removed and how much material is removed from thetibial surface. Alternatively, the assessment of the loading anddifferential between compartments can indicate that soft tissue releaseis sufficient to bring the joint within predetermined ranges forabsolute load and balance.

A further benefit of dynamic distractor 100 is in soft tissue release tomodify loading measured by sensors 108 and 110 and the differential(e.g. balance) between the measured values in each compartment. Dynamicdistractor 100 remains in place while soft tissue release is beingperformed allowing for real time measurement and modification to occur.The feedback to the surgeon is immediate as the soft tissue cuts aremade. Two issues are resolved by dynamic distractor 100. An open areaformed between the interior surfaces of upper support structure 202 andlower support structure 204 under distraction provides surgical access.In most cases, the gap is sufficient to allow a scalpel or blade accessto the lateral or medial ligaments for soft tissue release in the gap orperipheral to dynamic distractor 100. In general, soft tissue releaserequires anterior access to the joint space. Handle 112 of dynamicdistractor 100 can be removed providing further anterior access to thejoint. Alternatively, handle 112 is hinged or includes a joint allowingit to be positioned away from the surgical area. Thus, dynamicdistractor 100 enables soft tissue release by the surgeon to adjust theabsolute loading measured by sensors 108 and 110 in each compartment tobe within a predetermined range and to adjust the difference incompartment loadings within a predetermined range without removing thedevice.

FIG. 5 is a lateral view of dynamic distractor 100 in a knee jointpositioned in flexion in accordance with an exemplary embodiment. In anon-limiting example, load and balance measurements are performed usingdynamic distractor 100 with the leg in at least two positions (e.g. theleg in extension and the leg in flexion). For example, measurements aretaken in extension as disclosed hereinabove and in flexion with the legpositioned having femur 402 forming a 90 degree angle to tibia 404. Inone embodiment, accelerometers in sensors 108 and 110 are used todetermine relative positioning of the femur and tibia to one another.Under user control, measurements are taken at several points over therange of motion with dynamic distractor 100 in place therebysubstantially simplifying a data collection process. Measurements overthe range of motion can be taken when the femoral implant has beeninstalled or if the distal femur has not been modified. Alternatively,dynamic distractor 100 can be reduced in height by rotating handle 112until there is sufficient room to move the leg to a new position andthen increasing the height of distractor 100 to create the appropriategap.

A drop alignment rod 502 is placed through opening 114 of handle 112.Drop alignment rod 502 is a visual aid for the surgeon to ensure thatthe leg is aligned adequately when the load and balance measurements aretaken. Drop alignment rod 502 is used in conjunction with a knowledge ofthe leg mechanical axis or with markers placed on the patient to checkalignment. The surgeon aligns alignment rod 502 to the leg mechanicalaxis and makes a subjective determination that the leg is correctlypositioned. The surgeon can increase accuracy by pre-identifying pointson the mechanical axis. The surgeon has the option of making adjustmentsif drop alignment rod 502 indicates a potential positional error. Dropalignment rod 502 can be tapered having a section with a greater widththan opening 114 to retain it in place and prevent it from fallingthrough. Other embodiments to retain drop alignment rod 502 can also beused.

Alternatively, drop alignment rod 502 can be a smart alignment aid forthe surgeon that incorporates electronics similar to that described inFIG. 2. In general, drop alignment rod includes sensors to allowdepiction of the mechanical axis. For example, drop alignment rod 502can incorporate sensors to identify position in three-dimensional space.The electronics would allow drop alignment rod 502 to communicate withpre-operative defined locations or locations that are identified at thetime of surgery using locator electronics. The drop rod can house lightemitters to depict an axis as will be discussed in more detailhereinbelow. The electronics can include communication to externalprocessing unit 406 with a graphic user interface that has themechanical axis loaded therein.

FIG. 6 is a lateral view of a dynamic distractor 100 in a knee jointcoupled to a cutting block 602 in accordance with an exemplaryembodiment. In general, the surgeon utilizes surgical tools to obtainappropriate bony cuts to the skeletal system. The surgical tools areoften mechanical devices used to achieve gross alignment of the skeletalsystem prior to or during an implant surgery. In the knee example,mechanical alignment aids are often used during orthopedic surgery tocheck alignment of the bony cuts of the femur and tibia to themechanical axis of the leg. The mechanical alignment aids are notintegrated together, take time to deploy, and have limited accuracy.Dynamic distractor 100 in concert with cutting block 602 is anintegrated system for achieving alignment that can greatly reduce set uptime thereby minimizing stress on the patient.

As illustrated, the leg is in flexion having a relational position of 90degrees between femur 402 and tibia 404. A femoral rod 608 is coupledthrough the intermedullary canal of femur 402. A cutting block 602 isattached to the femoral rod 608 for shaping a portion of the surface ofthe distal end of femur 402 for receiving a femoral implant. Kneereplacement surgery entails cutting bone a certain thickness andimplanting a prosthesis to allow pain relief and motion. During thesurgery, instruments are used to assist the surgeon in performing thesurgical steps appropriately. Dynamic distractor 100 aids the surgeon byallowing quantitative measurement of the gap and parameter measurementduring all stages of the procedure. For the knee, the data cansupplement a surgeon's “feel” by providing data on absolute loading ineach compartment, the load differential between compartments, positionalinformation, and alignment information.

The portion of the surface of the distal end of femur 402 in contactwith dynamic distractor 100 is shaped in a subsequent step. In anon-limiting example, the portion of the condyles in contact withsuperior surface 102, sensor 108, and sensor 110 are the naturalcondyles of the femur. The portion of the distal end of femur 402 beingshaped corresponds to the condyle portion that would be in contact withthe final spacer while the leg is in extension and partially through therange of motion. In at least one exemplary embodiment, an uprod 604 ofdynamic distractor 100 couples to cutting block 602. Uprod 604 aids inthe alignment of the cutting block 602 to dynamic distractor 100 andtibia 404. Uprod 604 further stabilizes cutting block 602 to preventmovement as the distal end of femur 402 is shaped.

In one embodiment, handle 112 is removed and an uprod 604 is attached tothreaded rod 212. The uprod 604 can include a hinge that positions rod604 vertically to mate with cutting block 602. Alternatively, handle 112can include a hinge. In this example, handle 112 is uprod 604 and isinserted into cutting block 602. Furthermore, uprod 604 can be fastenedor coupled to an opening or feature in handle 112 to couple to cuttingblock 602. In general, uprod 604 is placed at a right angle to theinferior surface of lower support structure 204 of dynamic distractor100. In a prior step, the leg alignment can be checked to ensure it iswithin a predetermined range of the mechanical axis. In one embodiment,uprod 604 aligns approximately to the mechanical axis to secure cuttingblock 602 in an appropriate geometric orientation. Cutting block 602includes a channel 606 for receiving uprod 604. Uprod 604 can beadjustable in length that simplifies insertion. As previously mentioned,uprod 604 is attached to dynamic distractor 100 to align with themechanical axis of the leg corresponding to tibia 404. Fitted in theopening and into channel 606, uprod 604 maintains a positionalrelationship between cutting block 602, dynamic spacer block 100, femur402, and tibia 404. More specifically, the proximal surface of tibia 404is aligned to the mechanical axis thereby fixing the position of femur402 and cutting block 602 in a similar fixed geometric relationalposition. Thus, the distal end of femur 402 is cut having surfacesparallel to the proximal tibial surface by coupling dynamic distractor100 to cutting block 602 through uprod 604.

FIG. 7 is an anterior view of a cutting block 602 coupled to dynamicdistractor 100 in accordance with an exemplary embodiment. Cutting block602 is attached to the distal end of femur 402. Femoral rod 608 extendsthrough cutting block 602 into the intermedullary canal. Uprod 604 isshown extending vertically into channel 606 of cutting block 602. Incombination, femoral rod 608 and uprod 604 prevent movement and maintainalignment of the cutting block to the leg mechanical axis. As shown,cutting block 602 is illustrated as rectangular in shape. Cutting block602 is shaped to form a predetermined bone shape on the distal end offemur 402 for receiving a femoral implant. Thus, the shape of cuttingblock 602 can vary significantly from that shown depending on theimplant. The size of the cutting block 602 corresponds to the distal endsize and the femoral implant selected by the surgeon. The surgeon uses abone saw to remove portions of the distal end of femur 402 inconjunction with cutting block 602. In general, the cutting block 602acts as a template to guide the bone saw and to cut the distal end ofthe femur in a predetermined geometric shape. As disclosed previously inthe example, the portion of the distal end of femur 404 that is shapedcorresponds to the contact portion of the condyles when the leg is infull extension and partially in flexion (e.g. <90 degrees). As mentionedpreviously, the portion of the distal end of femur 402 in contact thesuperior surface 102 of dynamic distractor 100 is shaped in a subsequentstep.

FIG. 8 is an illustration of dynamic distractor 100 including alignmentin accordance with an exemplary embodiment. Dynamic distractor 100includes one or more recesses 802 in a handle 804 for receiving analignment aid to align a leg along the mechanical axis. In oneembodiment, handle 804 can be handle 112 that includes recesses 802.Alternatively, handle 804 is a separate handle for dynamic distractor100. Prior to checking alignment, handle 112 is removed from dynamicdistractor 100. Handle 804 is coupled to threaded rod 212.

Initial bony cuts are made in alignment with the mechanical axis of theleg. In the knee example, the alignment aid is used to check that thefemur and the tibia are correctly oriented prior to cutting. Thesurfaces of the bones are cut in alignment to the mechanical axis usinga jig. Thus, the cut surfaces on the distal end of the femur and theproximal end of the tibia are aligned and can be used as a referencesurfaces during the procedure. Alternatively, the alignment aid can beused to verify alignment throughout the procedure. Recesses 802 can bethru-holes in handle 804. In a non-limiting example, the alignment aidis one or more lasers 808. Lasers 808 are used to point along themechanical axis of the leg. In one embodiment, lasers 808 are used tocheck alignment of the leg. A first laser is used to point in thedirection of the hip joint. A second laser is used to point towards theankle. In one embodiment, the first and second lasers are integratedinto a single body. Handle 804 further comprises a hinge 806 to changethe angle at which lasers 808 are directed. The housing of lasers 808includes a power source such as a battery to generate the monochromaticlight beam. The housing fits within one of recesses 802 or a thru-hole.Lasers 808 can be a disposable item that is discarded after the surgeryis completed.

FIG. 9 is a side view of a leg in extension with dynamic distractor 100in the knee joint region in accordance with an exemplary embodiment. Themechanical axis of the leg is approximately a straight line from thecenter of the femoral head through the knee joint and extending to themiddle of the ankle joint. In a correctly aligned knee joint, themechanical axis will pass approximately through the center of the kneejoint. Alignment can be checked when dynamic distractor 100 ispositioned in the knee joint region. As illustrated, the leg is inextension with handle 804 extending vertically from the knee jointregion. In one embodiment, a target 902 is placed in an ankle or toeregion of the foot in a path corresponding to center of the ankle on themechanical axis of the leg. Similarly, a target 904 is placed in a pathcorresponding to the center of the head of the femur on the mechanicalaxis of the leg. Targets 902 are placed at a height similar to that oflasers 808. Lasers 808 are installed in the handle with one pointing inthe direction of the hip joint and another pointing in the direction ofthe ankle joint. From the top view, lasers 808 send out a beam of lightfrom a position that corresponds to the center of the knee. In oneembodiment, the direction of the beam from lasers 808 is directedperpendicular to a plane of the prepared surface of the proximal end ofthe tibia.

Lasers 808 are directed perpendicular to the inferior surface of dynamicdistractor 100. The placement of dynamic distractor 100 on the preparedtibial surface is such that handle 804 extends vertically at a pointcorresponding to the center of the knee joint. The leg is alignedcorrectly when the beams from lasers 808 hit the target at the pointscorresponding to the center of the head of the femur and the center ofthe ankle. Lasers 808 are positioned to align with the center of theknee joint. The surgeon can make adjustments to the bone surfaces orutilize soft tissue release to achieve alignment with the leg mechanicalaxis when lasers 808 are misaligned to the target. The system can beused to give a subjective or a measured determination on leg alignmentin relation to a vargus or valgus alignment. The direction ofmisalignment in viewing targets 902 and 904 will dictate the type ofcorrection and how much correction needs to be made. In an alternateembodiment, lasers 808 can be aimed such that the beam is viewable alongthe leg in a region by the center of the femoral head and the center ofthe angle. The surgeon can use this as a subjective visual gauge todetermine if the leg is in alignment to the mechanical axis and respondappropriately, depending on what is viewed.

FIG. 10 is a top view of a leg in extension with dynamic distractor 100in the knee joint area in accordance with an exemplary embodiment.Dynamic distractor 100 can measure spacing between the distal end of thefemur and the tibia, loading in each compartment, and differentialloading between compartments. The data can be sent to a processing unitand display as disclosed hereinabove. As mentioned previously, themechanical axis of the leg corresponds to a straight line from thecenter of the ankle, through the center of the knee, and the center ofthe femoral head. Targets 902 and 904 are respectively located overlyingthe mechanical axis in an area local to the ankle and the hip regions.Targets 902 and 904 can include a fixture such as a strap, brace, or jigto hold the targets temporarily along the mechanical axis. Lasers 808are enabled and placed in handle 804. The figure illustrates thattargets 902 and 904 are on approximately the same plane as beams emittedby lasers 808 such that the beams impinge on a target unless grosslymisaligned. Targets 902 and 904 can include calibration markings toindicate a measure of the misalignment. Alternatively, handle 804 ishinged allowing adjustment of the angle at which the beam from lasers808 is directed. The direction of the lasers 808 corresponds to theplane of the bone cuts for the implant and the balance of the joint.Thus, the surgeon using a single device has both quantitative andsubjective data relating to alignment to the mechanical axis, loading,balance, leg position, and gap measurement that allows gross/fine tuningduring surgery that results in more consistent orthopedic outcomes.

FIG. 11 is an illustration of a system 1100 for measuring one or moreparameters of a biological life form in accordance with an exemplaryembodiment. In a non-limiting example, the system provides real timemeasurement capability to a surgeon of one or more parameters needed toassess a muscular-skeletal system. System 1100 comprises a plurality ofspacer blocks 1102, a distractor 1104, sensors 1106, targets 1110,lasers 1114, a charger 1116, a receiver 1118, a reader 1120, aprocessing unit 1122, a display 1124 a drop rod 1126, an uprod 1128, acutting block 1130, a handle 1132, a dynamic data repository andregistry 1134. The system is adaptable to provide accurate measurementsof parameters such as distance, weight, strain, pressure, wear,vibration, viscosity, and density to name but a few. In one embodiment,system 1100 is used in orthopedic surgery and more specifically toprovide intra-operative measurement during joint implant surgery. System1100 is adapted for orthopedic surgery and more specifically for kneesurgery to illustrate operation of the system.

In general, system 1100 provides alignment and parameter measurementsystem for providing quantitative measurement of the muscular-skeletalsystem. In one embodiment, system 1100 is integrated with tools commonlyused in orthopedics to reduce an adoption cycle to utilize newtechnology. System 1100 replaces standalone equipment or dedicatedequipment that is used only for a small number of procedures thatjustifies the extra time and set up required to use this type ofequipment. Furthermore, it is well known, that dedicated equipment cancost hundreds of thousands or millions of dollars for a single device.Many hospitals and other healthcare facilities cannot afford the highcapital cost of these types of systems. Moreover, specialized equipmentsuch as robotic systems or alignment systems for orthopedic surgerytypically has a large footprint. The large footprint creates space andcost issues. The equipment must be stored, set up, calibrated, placed inthe operating room, and then removed.

Conversely, measurement and alignment components of system 1100 are lowcost disposables that make the measurement technology more accessible tothe general public. There is no significant capital investment requiredto use the system. Moreover, payback begins immediately with use inproviding quantitative information related to procedures therebyallowing analysis of outcomes based how the parameters being measuredaffect the procedure being measured. The data is used to initiatepredetermined specifications for the procedure that can be measured andadjusted during the course of the procedure thereby optimizing theoutcomes and reducing revisions. As mentioned previously, system 1100can be used or integrated with tools that the majority of orthopedicsurgeons have substantial experience or familiarity using on a regularbasis. In one embodiment, sensors 1106 are placed in a spacer thatseparates two surfaces of the muscular-skeletal system. In anon-limiting example, the spacer can be spacer blocks 1102 or distractor1104. A measurement of the parameter is taken after the spacer isinserted between at least two surfaces of the muscular-skeletal system.Sensors 1106 are in communication with processing unit 1122. In oneembodiment, the processing unit 1122 is outside the sterile field andincludes display 1124 and a GUI to provide the data in real time to thesurgeon. Thus, the learning cycle can be very short to provide real timequantitative feedback to the surgeon as well as storing the data forsubsequent use.

In a non-limiting example a spacer separates two surfaces of themuscular-skeletal system. The spacer has an inferior surface and asuperior surface that contact the two surfaces. The spacer can have afixed height or can have a variable height. The fixed height spacer isknown as spacer blocks 1102. Each spacer block 1102 has a differentthickness. The variable height spacer is known as the distractor 1104.The surface area of spacer blocks 1102 and distractor 1104 that coupleto the surfaces of the muscular-skeletal system can also be provided indifferent sizes. The handle 1132 extends from the spacer and typicallyresides outside or beyond the two surface regions. The handle 1132 isused to direct the spacer between the two surfaces. In one embodiment,the handle 1132 operatively couples to a lift mechanism of thedistractor 1104 to increase and decrease a gap between the superior andinferior surfaces of the spacer. The spacer and handle 1132 is part ofsystem 1100 to measure alignment of the muscular-skeletal system. In oneembodiment, at least one of the surfaces of the muscular-skeletal systemthat contacts the spacer has an optimal alignment to a mechanical axisof the muscular-skeletal system. The system measures the surface tomechanical axis alignment. In a non-limiting example, the misalignmentcan be corrected by a surgeon when the surface is misaligned to themechanical axis outside a predetermined range as disclosed below.

Knee replacement surgery entails cutting bone having a predeterminedspacing and implanting a prosthesis to allow pain relief and motion.During the surgery, instruments are used to assist the surgeon inperforming the surgical steps appropriately. The majority of surgeonscontinue to use passive spacers to aid in defining the gaps between thecut bones. The thickness of the final insert is selected after placingone or more trial inserts in the artificial joint implant. Thedetermination of whether the implanted components are correctlyinstalled is still to a large extent by “feel” of the surgeon throughmovement of the leg. In general, spacer blocks 1102 and distractor 1104of system 1100 is a spacer having an inferior and superior surface thatseparate at least two surfaces of the muscular-skeletal system. In theknee example, the inferior and superior surfaces are inserted betweenthe femur and tibia of the knee. At least one of the inferior orsuperior surfaces of spacer blocks 1102 and distractor 1104 have acavity or recess for receiving sensors 1106. In one embodiment, thecavity is on the superior surface of spacer blocks 1102 and distractor1104. A gap between the surfaces of distractor 1104 is adjustable asdescribed hereinabove. Tray 1108 includes multiple spacer blocks 1102each having a different thickness. Thus, spacer blocks 1102 anddistractor 1104 provide the surgeon with more than one option to measurespacing, alignment, and loading during the procedure. A benefit of thesystem is the familiarity that the surgeon will have with using similartype devices thereby reducing the learning curve to utilize system 1100.Furthermore, system 1100 can comprise spacer blocks 1102 and distractor1104 having spacer blocks having different sized superior and inferiorsurface areas to more readily accommodate different bone shapes andsizes.

In general, a rectangle is formed by the bony cuts during surgery. Theimaginary rectangle is formed between the cut distal end of a femur andthe cut proximal end of tibia in extension and in conjunction with themechanical axis of the lower leg. The prepared surfaces of the femur andtibia are shaped to respectively receive a femoral implant and a tibialimplant. The femoral and tibial surfaces are parallel to one anotherwhen the leg is in extension and in flexion at 90 degrees. Apredetermined width of the rectangle is the spacing between the planarsurface cuts on femur and tibia. The predetermined width corresponds tothe thickness of the combined orthopedic implant device comprising thefemoral implant, an insert, and the tibial implant. A target thicknessfor the initial cuts is typically on the order of twenty millimeters.The insert is inserted between the installed femoral implant and thetibial implant. In a full knee implant the insert has two bearingsurfaces that are shaped to receive the condyle surfaces of the femoralimplant.

In at least one exemplary embodiment, sensors 1106 can measure load andposition. Sensors 1106 are placed in a charger 1116 prior to the implantsurgery being performed. Charger 1116 provides a charge to an internalpower source within sensors 1106 that will sustain sensor measurementand data transmission throughout the surgery. Charger 1116 can fullycharge sensor 1106 or be used as a precautionary measure to insure thetemporary power storage is holding sufficient charge. Charger 1116 canbe charge via a wireless connection through a sterilized packaging.Sensors 1106 are in communication with processing unit 1122. Sensors1106 include a transmitter for sending data. Processing unit 1122 can belogic circuitry, a digital signal processor, microcontroller,microprocessor, or part of a system having computing capability. Asshown, processing unit 1122 is a notebook computer having a display1124. The communication between sensors 1106 and processing unit 1122can be wired or wireless. In one embodiment, receiver 1118 is coupled toprocessing for wireless communication. A carrier signal for datatransmitted from sensors 1106 can be radio frequency, infrared, optical,acoustic, and microwave to name but a few. In a non-limiting example,receiver 1118 receives data via a radio frequency signal in a shortrange unlicensed band sufficient for transmission within the size of anoperating room. Information from processing unit 1122 can be sentthrough the internet to dynamic data repository and registry 1134 forlong-term storage. The dynamic data repository and registry 1134 will bediscussed in greater detail hereinbelow. In one embodiment, the data isstored in a server 1136 or as part of a larger database.

The surgeon uses system 1100 to aid in the preparation of bone surfaces,to measure loading, to measure balance, check alignment, and tune theknee joint prior to a final insert being installed. A reader 1120 isused to scan in information prior to or during the surgery. In oneembodiment, the reader 1120 can be wired or wirelessly coupled to theprocessing unit 1122. Processing unit 1122 can process the information,display it on display 1124 for use during a procedure, and store it inmemory or a database for long-term use. For example, information oncomponents used in the surgery such as the artificial knee components orcomponents of system 1100 can be converted to an electronic digital formusing reader 1120 during the procedure. Similarly, patient informationor procedural information can also be scanned in, input manually, orcaptured by other means to processing unit 1122.

The leg is placed in extension and the knee joint is exposed byincision. In one embodiment, the surgeon prepares the proximal end ofthe tibia. The prepared tibial surface is typically at a 90-degree angleto the mechanical axis of the leg. Targets 1110 are placed overlying themechanical axis near the ankle and hip joint. The surgeon can select oneof the spacer blocks 1102 or dynamic distractor 1104 for insertion inthe joint region. The selected spacer block has a predeterminedthickness that is imprinted on the spacer block or can be displayed ondisplay 1124 by scanning the information. Alternatively, distractor 1104is distracted by the surgeon within the joint region. The amount ofdistraction can be read off of distractor 1104 or can be displayed ondisplay 1124.

In a non-limiting example of aligning two surfaces of themuscular-skeletal system, alignment of the leg to the mechanical axis ismeasured or a subjective check can be performed by the surgeon using analignment aid. At least one component of the alignment aid isdisposable. The alignment aid comprises lasers 1114 in the handle 1112of the selected spacer block or a handle 1132 of distractor 1104 withthe leg in extension. The alignment aid further includes targets 1110.Targets 1110, lasers 1114, or both can be disposable. Accelerometers insensors 1106 provide positional information of the tibia in relation tothe femur. For example, display 1124 will indicate that the anglebetween the tibia and femur is 180 degrees when the leg is in extension.The beam from lasers 1114 hit targets 1110 and provides a measurement ofthe position of the tibia in relation to the femur compared to themechanical axis of the leg. In one embodiment, lasers 1114 are centrallylocated above the knee joint overlying the mechanical axis of the leg.The beam from lasers 1114 is directed perpendicular to the plane of thesurface of the tibia. The beam from lasers 1114 will align and overliethe mechanical axis if the surface of the tibia is the perpendicular tothe mechanical axis. The beam from lasers 1114 would hit targets 1110 ata point that indicates alignment with the mechanical axis. A valgus orvargus reading can be read where the beam hits the calibrated markingsof targets 1110 if the leg is not aligned. The surgeon can then make anadjustment to bring the leg into closer alignment to the mechanical axisif deemed necessary. Jigs or cutting blocks can also be used inconjunction with lasers 1114 and targets 1110 to check alignment priorto shaping. The jigs or cutting blocks are used to shape the bone forreceiving an implant. The distal end of femur and the proximal end oftibia are shaped for receiving orthopedic joint implants. In a furtherembodiment, sensors can be attached to the cutting jigs or devices toaid the surgeon in optimizing the depth and angles of their cuts.

Sensors 1106 measure the loading in each compartment for the depth orthickness of the selected spacer block or the distracted gap generatedby distractor 1104. In one embodiment, the loading measurements aretaken after the initial bone cuts are determined to be within apredetermined range of alignment with the mechanical axis. The loadmeasurement in each compartment is either high, within an acceptablepredetermined range, or low. A load measurement above a predeterminedrange can be adjusted by removing bone material, selecting a thinnerspacer block, adjusting the gap of distractor 1104, or by soft tissuerelease. In general, the gap between the femur and tibia at which themeasurement taken corresponds to a final insert thickness. In oneembodiment, the gap is selected to result in a load measurement on thehigh side of the predetermined range to allow for fine-tuning throughsoft tissue release. Conversely, a load measurement below thepredetermined range can be increased using the next thicker spacer blockor by increasing the gap of distractor 1104. Data from sensors 1106 istransmitted to processing unit 1122. Processing unit 1122 processes thedata and displays the information on display 1124 for use by the surgeonto aid in fine-tuning. Display 1124 would further provide positionalinformation of the femur and tibia. The absolute loading in eachcompartment is measured and displayed on display 1124. As is known byone skilled in the art, the gap created by the bone cuts accommodatesthe combined thickness of the femoral implant, the tibial implant, andthe insert. The gap using spacer blocks 1102 or distractor 1104 takesinto account the combined thickness of the implant components. In anon-limiting example, the gap is chosen based on the availability ofdifferent thicknesses of the final insert. Thus, the loading on thefinal or permanent insert placed in the joint will measure within thepredetermined range as prepared by using system 1100.

Balance is a comparison of the load measurement of each condyle surface.In general, balance correction is performed when the measurements exceeda predetermined difference value. Soft tissue balancing is achieved byloosening ligaments on the side of the compartment that measures ahigher loading. In one embodiment, system 1100 allows the surgeon toread the loading measurement for each compartment on one or moredisplays on spacer blocks 1102 or distractor 1104. Another factor isthat the difference in loading can be due to surface preparation of thebony cuts for either femoral implant or the tibial implant. If thedifferential is substantial, the surgeon has the option of removing boneon either surface underlying the implant to reduce the loadingdifference.

In one embodiment, the absolute load adjustments and balance adjustmentsare performed by soft tissue release in response to the assessment ofeach compartment. Load and balance adjustment is achieved with theselected spacer block or distractor 1104 in the knee joint. Spacerblocks 1102 and distractor 1104 have a gap to provide peripheral accessbetween the superior and inferior surfaces of the device thereby givingthe surgeon access to perform soft tissue release to either compartmentwith real time load measurement shown on display 1124. In at least oneexemplary embodiment, handles 1112 of spacer blocks 1102 or handle 1132of distractor 1104 can be removed or positioned. Handles 1112 or handle1132 can be positioned away from the surgical area or removed allowingthe surgeon access to perform soft tissue release. The soft tissuerelease is performed to each compartment to adjust the absolute loadingwithin the predetermined range and further adjustment can be performedto reduce the differential loading between the compartments to within apredetermined differential range. Consequently, the surgical outcome isa function of system 1100 as complemented with the surgeon's abilitiesbut not so highly dependent alone on the surgeon's skill. The devicecaptures the “feel” of how an implanted device should properly operateto improve precision and minimize variation including haptic and visualcues.

A similar process is applied with the lower leg in flexion with tibiaforming a 90-degree angle with the femur. In one embodiment, one or morebone cuts are made to the distal end of femur for receiving the femoralimplant. The preparation of the femur corresponds to the leg inextension. As disclosed above, the selected spacer block or distractor1104 can be coupled using an uprod from handle 1112 or handle 1132 tocutting block 1130 to aid in alignment and stability. In particular, thesurface of the distal end of femur is cut parallel to the preparedsurface of the tibia with the leg in flexion. The bone cut to the femuryields an imaginary rectangle formed with the parallel surfaces of femurand tibia when the leg is in extension. It should be noted that aportion of the femoral condyle is in contact with the selected spacerblock or distractor 1104 with the leg in flexion and this region is notprepared at this time. In a subsequent step, the remaining surface ofthe distal end of the femur is prepared. The width of the gap inextension and in flexion between the cut distal end of the femur and theprepared tibia surface corresponds to the thickness of the combinedorthopedic implant device comprising the femoral implant, final insert,the tibial implant. Ideally, the measured the gap under equal loading inflexion (e.g. the tibia forms a 90 degree angle with the femur) andextension is similar or equal. The prepared femoral surfaces and theprepared tibial surfaces are parallel throughout the range of motion andperpendicular to the mechanical axis of the leg.

Load measurements are made with the leg in flexion and the selectedspacer block or distractor 1104 between the distal end of the femur andthe tibial surface. In a non-limiting example, the measurements asdescribed above should be similar to the measurements made in extension.Adjustments to the load value and the balance between compartments canbe made by soft tissue release, or femoral component rotation in flexionwith the selected spacer block or distractor 1104 in place.Alternatively, the femoral implant can be seated on the distal end ofthe femur and measurements taken. Adjustments can be made with thefemoral implant in place. Furthermore, a gap generated by distractor1104 can be adjusted to accommodate differences due to the femoralimplant if required.

The leg with the selected spacer block or distractor 1104 can be takenthrough a complete range of motion. The loading in each compartment canbe monitored on display 1124 and processed by processing unit 1122 overthe range of motion. Processing unit can compare different points in therange of motion to the predetermined load range and the predetermineddifferential load range. Should an out of range/value condition occur,the surgeon can view and note the position of the femur and tibiaposition on display 1124 and take steps to bring the implant withinspecification. The surgeon can complete the implant surgery havingknowledge that both qualitative and quantitative information was usedduring the procedure to ensure correct installation. In one embodiment,sensors 1106, disposable targets 1110, and lasers 1114 are disposed ofupon completion of the surgery.

For example, the sensors will enable the surgeon to measure jointloading while utilizing soft tissue tensioning to adjust balance andmaximize stability of an implanted joint. Similarly, measured data inconjunction with positioning can be collected before and during surgeryto aid the surgeon in ensuring that, the implanted device has anequivalent geometry and range of motion.

Element 1340 of FIG. 12 depicts an exemplary diagrammatic representationof a machine in the form of a computer system 1200 within which a set ofinstructions, when executed, may cause the machine to perform any one ormore of the methodologies discussed above. In some embodiments, themachine operates as a standalone device. In some embodiments, themachine may be connected (e.g., using a network) to other machines. In anetworked deployment, the machine may operate in the capacity of aserver or a client user machine in server-client user networkenvironment, or as a peer machine in a peer-to-peer (or distributed)network environment.

The machine may comprise a server computer, a client user computer, apersonal computer (PC), a tablet PC, a laptop computer, a desktopcomputer, a control system, a network router, switch or bridge, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by that machine. It will beunderstood that a device of the present disclosure includes broadly anyelectronic device that provides voice, video or data communication.Further, while a single machine is illustrated, the term “machine” shallalso be taken to include any collection of machines that individually orjointly execute a set (or multiple sets) of instructions to perform anyone or more of the methodologies discussed herein.

The computer system may include a processor (e.g., a central processingunit (CPU), a graphics processing unit (GPU, or both), a main memory anda static memory, which communicate with each other via a bus. Thecomputer system may further include a video display unit (e.g., a liquidcrystal display (LCD), a flat panel, a solid-state display, or a cathoderay tube (CRT)). The computer system may include an input device (e.g.,a keyboard), a cursor control device (e.g., a mouse), a disk drive unit,a signal generation device (e.g., a speaker or remote control) and anetwork interface device.

The disk drive unit may include a machine-readable medium on which isstored one or more sets of instructions (e.g., software) embodying anyone or more of the methodologies or functions described herein,including those methods illustrated above. The instructions may alsoreside, completely or at least partially, within the main memory, thestatic memory, and/or within the processor during execution thereof bythe computer system. The main memory and the processor also mayconstitute machine-readable media.

Dedicated hardware implementations including, but not limited to,application specific integrated circuits, programmable logic arrays andother hardware devices can likewise be constructed to implement themethods described herein. Applications that may include the apparatusand systems of various embodiments broadly include a variety ofelectronic and computer systems. Some embodiments implement functions intwo or more specific interconnected hardware modules or devices withrelated control and data signals communicated between and through themodules, or as portions of an application-specific integrated circuit.Thus, the example system is applicable to software, firmware, andhardware implementations.

In accordance with various embodiments of the present disclosure, themethods described herein are intended for operation as software programsrunning on a computer processor. Furthermore, software implementationscan include, but not limited to, distributed processing orcomponent/object distributed processing, parallel processing, or virtualmachine processing can also be constructed to implement the methodsdescribed herein.

The present disclosure contemplates a machine readable medium containinginstructions, or that which receives and executes instructions from apropagated signal so that a device connected to a network environmentcan send or receive voice, video or data, and to communicate over thenetwork using the instructions. The instructions may further betransmitted or received over a network via the network interface device.

While the machine-readable medium is shown in an example embodiment tobe a single medium, the term “machine-readable medium” should be takento include a single medium or multiple media (e.g., a centralized ordistributed database, and/or associated caches and servers) that storethe one or more sets of instructions. The term “machine-readable medium”shall also be taken to include any medium that is capable of storing,encoding or carrying a set of instructions for execution by the machineand that cause the machine to perform any one or more of themethodologies of the present disclosure.

The term “machine-readable medium” shall accordingly be taken toinclude, but not be limited to: solid-state memories such as a memorycard or other package that houses one or more read-only (non-volatile)memories, random access memories, or other re-writable (volatile)memories; magneto-optical or optical medium such as a disk or tape; andcarrier wave signals such as a signal embodying computer instructions ina transmission medium; and/or a digital file attachment to e-mail orother self-contained information archive or set of archives isconsidered a distribution medium equivalent to a tangible storagemedium. Accordingly, the disclosure is considered to include any one ormore of a machine-readable medium or a distribution medium, as listedherein and including art-recognized equivalents and successor media, inwhich the software implementations herein are stored.

Although the present specification describes components and functionsimplemented in the embodiments with reference to particular standardsand protocols, the disclosure is not limited to such standards andprotocols. Each of the standards for Internet and other packet switchednetwork transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP) representexamples of the state of the art. Such standards are periodicallysuperseded by faster or more efficient equivalents having essentiallythe same functions. Accordingly, replacement standards and protocolshaving the same functions are considered equivalents.

The illustrations of embodiments described herein are intended toprovide a general understanding of the structure of various embodiments,and they are not intended to serve as a complete description of all theelements and features of apparatus and systems that might make use ofthe structures described herein. Many other embodiments will be apparentto those of skill in the art upon reviewing the above description. Otherembodiments may be utilized and derived therefrom, such that structuraland logical substitutions and changes may be made without departing fromthe scope of this disclosure. Figures are also merely representationaland may not be drawn to scale. Certain proportions thereof may beexaggerated, while others may be minimized. Accordingly, thespecification and drawings are to be regarded in an illustrative ratherthan a restrictive sense.

FIG. 12 and FIG. 13 illustrate a communication network 1300 formeasurement and reporting in accordance with an exemplary embodiment.Briefly, the communication network 1300 expands broad data connectivityto other devices or services. As illustrated, the measurement andreporting system 1300 can be communicatively coupled to thecommunications network 1300 and any associated systems or services.

As one example, the measurement system 1355 can share its parameters ofinterest (e.g., angles, load, balance, distance, alignment,displacement, movement, rotation, and acceleration) with remote servicesor providers, for instance, to analyze or report on surgical status oroutcome. This data can be shared for example with a service provider tomonitor progress or with plan administrators for surgical monitoringpurposes or efficacy studies. The communication network 1300 can furtherbe tied to an Electronic Medical Records (EMR) system to implementhealth information technology practices. In other embodiments, thecommunication network 1300 can be communicatively coupled to HISHospital Information System, HIT Hospital Information Technology and HIMHospital Information Management, EHR Electronic Health Record, CPOEComputerized Physician Order Entry, and CDSS Computerized DecisionSupport Systems. This provides the ability of different informationtechnology systems and software applications to communicate, to exchangedata accurately, effectively, and consistently, and to use the exchangeddata.

The communications network 1300 can provide wired or wirelessconnectivity over a Local Area Network (LAN) 1301, a Wireless Local AreaNetwork (WLAN) 1305, a Cellular Network 1314, and/or other radiofrequency (RF) system (see FIG. 4). The LAN 1301 and WLAN 1305 can becommunicatively coupled to the Internet 1320, for example, through acentral office. The central office can house common network switchingequipment for distributing telecommunication services. Telecommunicationservices can include traditional POTS (Plain Old Telephone Service) andbroadband services such as cable, HDTV, DSL, VoIP (Voice over InternetProtocol), IPTV (Internet Protocol Television), Internet services, andso on.

The communication network 1300 can utilize common computing andcommunications technologies to support circuit-switched and/orpacket-switched communications. Each of the standards for Internet 1320and other packet switched network transmission (e.g., TCP/IP, UDP/IP,HTML, HTTP, RTP, MMS, SMS) represent examples of the state of the art.Such standards are periodically superseded by faster or more efficientequivalents having essentially the same functions. Accordingly,replacement standards and protocols having the same functions areconsidered equivalent.

The cellular network 1314 can support voice and data services over anumber of access technologies such as GSM-GPRS, EDGE, CDMA, UMTS, WiMAX,2G, 3G, WAP, software defined radio (SDR), and other known technologies.The cellular network 1314 can be coupled to base receiver 1310 under afrequency-reuse plan for communicating with mobile devices 1302.

The base receiver 1310, in turn, can connect the mobile device 1302 tothe Internet 1320 over a packet switched link. The internet 1320 cansupport application services and service layers for distributing datafrom the measurement system 1355 to the mobile device 1302. The mobiledevice 1302 can also connect to other communication devices through theInternet 1320 using a wireless communication channel.

The mobile device 1302 can also connect to the Internet 1320 over theWLAN 1305. Wireless Local Access Networks (WLANs) provide wirelessaccess within a local geographical area. WLANs are typically composed ofa cluster of Access Points (APs) 1304 also known as base stations. Themeasurement system 1355 can communicate with other WLAN stations such aslaptop 1303 within the base station area. In typical WLANimplementations, the physical layer uses a variety of technologies suchas 802.11b or 802.11g WLAN technologies. The physical layer may useinfrared, frequency hopping spread spectrum in the 2.4 GHz Band, directsequence spread spectrum in the 2.4 GHz Band, or other accesstechnologies, for example, in the 5.8 GHz ISM band or higher ISM bands(e.g., 24 GHz, etc).

By way of the communication network 1300, the measurement system 1355can establish connections with a remote server 1330 on the network andwith other mobile devices for exchanging data. The remote server 1330can have access to a database 1340 that is stored locally or remotelyand which can contain application specific data. The remote server 1330can also host application services directly, or over the internet 1320.

It should be noted that very little data exists on implanted orthopedicdevices. Most of the data is empirically obtained by analyzingorthopedic devices that have been used in a human subject or simulateduse. Wear patterns, material issues, and failure mechanisms are studied.Although, information can be garnered through this type of study it doesyield substantive data about the initial installation, post-operativeuse, and long term use from a measurement perspective. Just as eachperson is different, each device installation is different havingvariations in initial loading, balance, and alignment. Having measureddata and using the data to install an orthopedic device will greatlyincrease the consistency of the implant procedure thereby reducingrework and maximizing the life of the device. In at least one exemplaryembodiment, the measured data can be collected to a database where itcan be stored and analyzed. For example, once a relevant sample of themeasured data is collected, it can be used to define optimal initialmeasured settings, geometries, and alignments for maximizing the lifeand usability of an implanted orthopedic device.

FIG. 14 is an exemplary method 1400 for distracting surfaces of themuscular-skeletal system in accordance with an exemplary embodiment. Themethod can be practiced with more or less than the number of steps shownand is not limited to the order shown. In general, a spacer can have afixed height or can be variable. The spacer is placed between surfacesof the muscular-skeletal system to distract or separate the surfaces.The spacer can include a handle to direct the spacer into themuscular-skeletal system. In one embodiment, the spacer is used toseparate a joint region. A spacer with a fixed height is also known as aspacer block. A spacer having variable height is known as a distractor.In one embodiment, a distractor includes a lift mechanism as disclosedherein that can precisely adjust a height between surfaces to create agap in the muscular-skeletal system of a predetermined value. A dynamicdistractor includes one or more sensors that can measure a parameter ofthe muscular-skeletal system in real time. A variable height spacer cancomprise a predetermined height in one state and a compressible heightin a second state. The second state allows compression of the spacer asthe muscular-skeletal system is moved from a first relational positionto a second relational position. The variable height spacer can then befixed to the predetermined height once positioned in the secondrelational position.

In a step 1402, sterilized sensors are removed from packaging. Thesensors are powered up and enabled for sensing. One or more sensorscoupled to a sensor for measuring a parameter of the muscular-skeletalsystem. For example, sensors are placed overlying a superior surface ofa dynamic distractor. In the example, the sensors are used to measureload and balance for a knee reconstruction procedure. In one embodiment,the sensors are placed in a cavity on the superior surface of thedistractor. Each sensor corresponds to a compartment of the knee. Thedynamic distractor is also in a sterilized condition.

In a step 1404, the spacer is inserted in the muscular-skeletal system.The surfaces of the spacer are in contact with surfaces ofmuscular-skeletal system to be distracted. The surfaces of themuscular-skeletal system are in a first relational position. Continuingwith the knee example, the inferior surface of the dynamic distractor iscoupled to the proximal end of the tibia and the superior surface iscoupled to the distal end of the femur. In one embodiment, the distalend of the tibia is prepared having a flat surface that is perpendicularto the mechanical axis of the leg.

In a step 1406, a dynamic distractor is used to vary a gap between thesurfaces of the muscular skeletal system. In the knee example, a handlecoupled to a lift mechanism of the dynamic distractor rotated toincrease a gap between the inferior and superior surfaces. As the gapincreases the inferior surface is in contact with the distal end of thetibia. Similarly, the superior surface of the dynamic distractorcontacts the distal end of the femur. In one embodiment, the condyles ofthe distal end of the femur or the condyles of a femoral implant contactthe corresponding sensors in each compartment of the dynamic distractor.The dynamic distractor is placed in the knee joint such that the dynamicdistractor is centrally located in the knee joint. In one embodiment,the mechanical axis of the leg aligns to a feature of the dynamicdistractor between the medial and lateral sides of the device. Thehandle of the dynamic distractor extends away from the knee joint on themechanical axis of the leg.

In a step 1408, a parameter is measured by the sensors. The parameter isa quantitative measurement such as distance, weight, strain, force,load, pressure, wear, vibration, viscosity, and density that relate andcharacterize the procedure being performed. For illustration purposesthe sensors measure load, pressure, or force. In the knee example, theloading in each compartment of the knee is measured at the height or gapcreated by the dynamic distractor. Similarly, the parameter measurementcan be taken using the sensors overlying a spacer of a predeterminedheight. In one embodiment, the gap or height of distraction relates tothe thickness of one or more components of an artificial joint such asthe knee joint. The gap can correspond to the thickness of a finalinsert of the artificial joint. In general, final inserts typicallycomprise a polymer that provide a low-friction low-wear bearing surface.The final inserts are typically provided in a number of predeterminedthicknesses of which one is selected for permanent insertion.

In a step 1410, the one or more sensors are removed from the spacer. Ingeneral, the sensor is removed after all quantitative measurements havebeen taken during the procedure. In a step 1412, the sensor is disposedof after the procedure is completed. For example, the sensors can beexposed to biological waste and require disposal as a biological hazard.The sensors as a disposable item alleviate substantial problems facingthe health care industry. The high capital cost of traditional ofsurgical equipment often prevent purchase thereby preventing potentiallybeneficial equipment from being used. Disposables also eliminate thecostly and time-consuming process of sterilization. The low cost of thesensors eliminates the capital cost issue thereby opening quantitativemeasurement of joint implants to a much larger audience. The result willbe more consistent surgeries, ability to fine tune the surgery, longerimplant life, and reduced post surgical complications to name but a few.

In general, a modification to the muscular-skeletal, a quantitativemeasurement, or both is performed with the surfaces of themuscular-skeletal in more than one relational position. In oneembodiment, the surfaces of the muscular-skeletal system are positionedin a first relational position. A modification to the muscular-skeletalsystem is performed. The modification can affect the parameter beingmeasured. In a step 1436, the two surfaces are positioned in a secondrelational position. In one embodiment, the spacer is not removed duringthe process of repositioning the surfaces of the muscular-skeletalsystem. A modification to the muscular-skeletal system, a quantitativemeasurement, or both can then be performed with the surfaces of themuscular-skeletal system in the second relational position.

Steps 1414, 1416, and 1418 illustrates an optimization process for aprocedure with the dynamic distractor. In the knee example, steps 1414,1416, and 1418 are an adjustment to optimize loading for a final insertof the artificial joint that maximizes the operating life of the device.The leg is placed in a first relational position. For example, the legis placed in extension with the femur and tibia aligned with amechanical axis of the leg. In general, it is not desirable for theimplanted joint to be too tight or loose. In a step 1414, the gap isincreased until the loading is within a predetermined loading range andthe gap corresponds to an available final insert thickness. In oneembodiment, the gap is selected for a final insert thickness thatmeasures a loading above the median of the predetermined range to allowfor soft tissue release back within the predetermined range. In a step1416, the gap is measured when the sensors measure loading within thepredetermined range. Alternatively, the dynamic distractor can increaseor decrease gaps incrementally that correspond to available inserts. Ina step 1418, the insert is selected. As mentioned previously, themeasured gap when the loading is within the predetermined range may notcorrespond to a final insert thickness. The surgeon can increase ordecrease the gap to an available insert thickness (and measure load ineach compartment) then select an insert based on subsequent steps of theprocedure to be implemented by the surgeon.

Steps 1420 and 1422 relate to adjustments made while a spacer isinserted. In one embodiment, the spacer is the dynamic distractor withone or more sensors. In a step 1420, data from the sensors istransmitted to a processing unit. In a non-limiting example, theprocessing unit is external to the dynamic distractor and sensors. Asdisclosed herein, the processing unit can be part of a notebookcomputer. The data from the sensors in the dynamic distractor can bedisplayed for viewing by the surgeon and medical team. In a step 1422,the surgeon can adjust the loading using soft tissue release techniqueswith the dynamic distractor in place. In one embodiment, the dynamicdistractor can have a bellows or removable skirt around the periphery ofthe device that prevents debris from collecting within the interior. Thebellows or removable skirt is removed to allow access along the medialand lateral periphery of the dynamic distractor and between the upperand lower support structures of the dynamic distractor. Further accessfor soft tissue release is provided by removing the handle of thedynamic distractor or positioning the handle away from the surgicalarea. Steps 1420 and 1422 can also be performed after the leg is movedinto the second relational position. In the knee example, the leg ismoved in flexion with the femur and tibia at less than a 180 degreeangle. For example, the leg is moved in flexion at a 90 degree angle.Bone modification of the exposed distal end of the femur can also bepreformed to prepare a bone surface for a femoral implant.

Steps 1424 and 1426 relate to adjustments made when parameters aremeasured in more than one region. In the knee example, measurements aremade in the two knee compartments corresponding to the medial andlateral condyles (natural or artificial) in contact with the sensors. Ina step 1424, the loading is measured in each compartment. In oneembodiment, the measured loading in the two regions should beapproximately equal. The differential loading can be measured and thenadjusted if outside a predetermined differential load range. In general,the side measuring the higher loading is adjusted. In a step 1426, softtissue release is performed to adjust the difference between theloadings measured in each compartment. As disclosed herein, the loadingcan be measured in real time as the release occurs. The loading is thenadjusted until the difference between the compartments is within thepredetermined differential load range thereby adjusting the jointtowards the optimum based on measurement. Steps 1424 and 1426 can alsobe performed after the leg is moved into the second relational position.It should be noted that other adjustment methods can also be used insteps 1422 and 1426 if soft tissue release cannot produce the desiredresult. In some cases, the dynamic distractor is removed for completeaccess to the joint region allowing more substantial modification tooccur.

Steps 1428, 1430, 1432, 1434, 1436, and 1438 relate to positioning andaligning the leg using the dynamic distractor. In step 1428, the leg ispositioned using position information provided by the dynamicdistractor. In one embodiment, accelerometers in the sensors provideinformation on the angle of the tibia in relation to the femur. Thus,the leg can be put precisely in extension (e.g. a 180-degree anglebetween the femur and tibia) and in flexion (less than 180-degree angle,for example a 90 degree angle between the femur and tibia). In a step430, the positional information can be sent to the processing unit andthe information displayed on a display for viewing by the surgeon. Thesurgeon can place the leg in extension or flexion to prepare or shapethe proximal end of the tibia or the distal end of the femur. In steps1432 and 1434, the surgeon identifies the mechanical axis of the leg. Inone embodiment, one or more lasers are coupled to the handle of thedynamic distractor in the knee joint. As mentioned previously, thehandle of the dynamic distractor is located overlying the center of theknee. In the step 1432, a first laser emits a signal to a first targetthat is positioned proximally to the center of the ankle. The line fromcenter of the ankle to the center of knee aligns with the mechanicalaxis of the leg. The first target is positioned where it overlies themechanical axis on a plane corresponding to the beam from the firstlaser. Similarly, in a step 1434, a second laser emits a signal to asecond target that is positioned proximally to the center of the femoralhead. A straight line from the center of the femoral head through thecenter of the knee to the center of the ankle comprises the mechanicalaxis of the leg. The second target overlies the mechanical axis and ispositioned on a plane corresponding to the beam from the second laser.The surgeon can then measure the misalignment of the leg to themechanical axis and make corrections appropriately.

FIG. 15 is an exemplary method 1500 for distracting surfaces of themuscular-skeletal system in extension and in flexion in accordance withan exemplary embodiment. The method can be practiced with more or lessthan the number of steps shown and is not limited to the order shown. Ina step 1502, a distractor is placed between surfaces of amuscular-skeletal system. As mentioned previously, the distractor can bebroadly used on the muscular-skeletal system including but not limitedto the spinal column, knee, hip, ankle, shoulder, wrist, articulating,and non-articulating structures. As disclosed above, the distractorcomprises a lift mechanism between a first support structure and asecond support structure. In one embodiment, a handle couples to thelift mechanism to rotatably raise and lower the lift mechanism therebychanging a gap between the surfaces of the support structures. Ingeneral, the first and second supports structures are placed between twosurfaces of the muscular-skeletal system. In a non-limiting example, toillustrate the principal, the distractor can be used in joint repair orreplacement surgery to separate bones comprising the joint as they areprepared for an implant. Examples are vertebrae of the spinal column,the distal end of the femur and the proximal end of the tibia of a kneejoint, or the pelvis and the proximal end of the femur of the hip.

In a step 1504, the gap provided by the distractor is changed and themuscular-skeletal system is placed in a first relational position. Thegap of the distractor can be changed under the control of the surgeonthereby changing the spacing between the two surfaces of themuscular-skeletal system being distracted. In one embodiment, the gapcorresponds to a thickness of one or more components to be implanted inthe muscular-skeletal system. The distractor is likely to be initiallyplaced between the two surfaces having a minimum gap and then expandedto a predetermined height or thickness. The muscular-skeletal system isplaced in a first relational position with the distractor insertedbetween the two surfaces. The first relation position corresponds to thepositions of the surfaces and portions of the muscular-skeletal systemattached thereto.

In a step 1506, at least one parameter is measured with a sensor. Themuscular-skeletal system is in the first relational position whenparameter is measured by the sensor. In one embodiment, the distractorincludes a sensor for measuring a parameter. For example, the sensor canprovide accurate measurements of parameters such as distance, weight,strain, pressure, wear, vibration, viscosity, and density that relate tothe procedure being performed. The distractor further provides two ormore surfaces in contact with the muscular-skeletal system for closeproximity measurement by the sensor. As disclosed hereinabove, thesensor can be self contained in a housing, can be placed in a cavity onone or more of the distracting surfaces and includes an exposed surfacethat can couple to the muscular-skeletal system for sensing.

In a step 1508, the muscular-skeletal system is repositioned to a secondrelational position. In a non-limiting example, the second relationalposition corresponds to movement of the distracted surfaces and portionsof the muscular-skeletal system attached thereto in relation to oneanother. The position of the distracted surfaces in the second positionis different from the position of the distracted surfaces in the firstposition. The distractor remains in place during positioning to thesecond relational position. This provides the benefit of reducingsurgical time and stress on the patient. In general, the supportstructures of the distractor and more specifically the surfaces of thesupport structure allow natural movement of the muscular-skeletal in anormal range of motion.

In a step 1510, at least one parameter is measured by the sensor whilein the second relational position. In one embodiment, the distractorremains in place while the measurement is taken. The surgeon or medicalstaff can compare measurement data with the muscular-skeletal system intwo different positions. Often the measurement data will be similarthroughout the range of motion or differ by a known amount due togeometrical differences of the position. Referring to a step 1518, thesensor can include a transmitter for transmitting measurement data fromthe sensor to a processing unit. The processing unit can be a logiccircuit, digital signal processor, microcontroller, microprocessor, oranalog circuitry. The processing unit can be part of a larger systemsuch as a multi-component custom system or a commercially availablenotebook computer or personal computer. In a step 1520, the measurementis displayed on a display. The data can be processed by the processingunit and a GUI (graphical user interface) integrated with the display topresent the data, enhance use of the data, interpret the data, andcontemplate or detail corrections that may be needed to be made based onthe data. The transmission of the data can occur as measurements over arange of motion and at least in the first relational position and thesecond relational position. In one embodiment, the distractor providesmeasurement data on the amount of distraction or gap produced by thedevice. This measurement data can also be transmitted along with therelational position data of the muscular-skeletal system. Thus, thedistractor provides the benefit of measurement data being taken with thesensor at different points of the range of motion and at different gapheights without being removed.

In a step 1512, the sensor is placed on a surface of the distractor. Inone embodiment, the sensor is a disposable device. The supportstructures of the distractor can have one or more recesses or cavitiesfor receiving a sensor on a surface of the device. In particular, acavity can be formed on a major surface of a support structure thatcomes in contact with a surface of the muscular-skeletal system duringdistraction. In a non-limiting example, one or more sensors are placedin one more cavities prior to insertion between the two surfaces of themuscular-skeletal system. The sensors are activated and in communicationwith the processing unit for taking measurements on themuscular-skeletal system. In a step 1514, the sensor is coupled to asurface of the muscular-skeletal system. As disclosed herein, the sensorcan include a major surface that is exposed and substantially parallelto the major surface of a support structure. The sensor comes in contactwith the muscular-skeletal system as the two surface of themuscular-skeletal system are distracted. Typically, as distractionincreases a compressive force by the two surfaces of themuscular-skeletal system is applied to the two support structuresplacing the sensor in intimate contact with the surface. Alternatively,the sensor can be located on or in proximity to the distractor if directcontact is not required for the measurement.

In a step 1522, the alignment of at least one of the first or secondrelational position is compared to a mechanical axis of themuscular-skeletal system. Typically, the muscular-skeletal system hasoptimal alignments that maximize performance of the structure. Thedistractor can be used to measure misalignment to the mechanical axis.The distractor utilizes at least one of the surface being distracted tomeasure the misalignment. The distracted surface of themuscular-skeletal system has a geometric relationship with themechanical axis. For example, the plane of the distracted surface can bea specific angle from the mechanical axis. Moreover, there can bespecific landmarks of the surface that such as a center point thatfurther identify the relationship with the mechanical axis.

In one embodiment, a plane of a portion of the surface of the distractoris co-planar with the muscular-skeletal surface it is contacting. Thisrelationship is extended to a handle of the distractor where a surfaceof the handle is co-planar to the distracted surface of themuscular-skeletal system. The handle can also extend frommuscular-skeletal system at a location corresponding to a landmark thatcorresponds to the mechanical axis. For example, it can extend centrallyor at a specific position from the distracted surface. As disclosedhereinabove, a drop rod can be attached to an opening in the handle tovisually and subjectively determine if alignment is within apredetermined range. The drop rod can also be coupled to other fixturescoupled to different areas of the muscular-skeletal system to measurealignment. Alternatively, one or more lasers can be attached to thehandle of the distractor. The lasers are directed to one or more targetsthat are located along the mechanical axis. The amount of misalignmentcan be measured by the location where the beam hits a scale on each ofthe target.

In a step 1524, the muscular-skeletal system is modified to reduce themeasured misalignment. In general, there will be an acceptable range formisalignment to the mechanical axis. Adjustments are made to reduce theerror if the measurement is outside the acceptable range. Modificationsto the muscular-skeletal system can take many forms. Material can beadded or removed from the bone structure. Soft tissue release of themuscles, tendons, and ligaments can also be used to modify alignment.Additionally, other structures and materials that are both biologicaland artificial can be used to change or be added to themuscular-skeletal system to bring the two surfaces into alignment. Afterthe modifications are performed, the alignment can be rechecked toverify that the misalignment error is with an acceptable range.

In a step 1526, the handle is used to direct the placement of thedistractor between the two surfaces of the muscular-skeletal system. Thehandle of the distractor provides an external means for the surgeon tolocate and position the first and second support structures of thedistractor accurately in the muscular-skeletal system. In oneembodiment, the handle is coupled to a lift mechanism that generates thegap between the first and second support structures. In a step 1528, thegap height can be varied using the handle. The handle is coupled to ashaft of the lift mechanism. In a non-limiting example, the handle isrotated to increase or decrease the gap of the distractor.

In a step 1530, the handle is moved away from the surgical area. Thedistractor is designed to provide access to areas in proximity to thetwo surfaces being distracted by the device. One access area is anteriorto the two surfaces of the distracted muscular-skeletal system. Accessis desirable to perform a surgical procedure or other step with thedistractor in place. A benefit of the distractor is that the handle ishinged allowing it to be moved away from the area where the surgicalprocedure is being performed. Alternatively, in a step 1536, the handleis removed from the distractor also giving unobstructed anterior access.The distractor also has peripheral access and access between the firstand second support structures when a gap is created. In one embodiment,the distractor has a bellows like skirt around the periphery of thedevice that is inserted between the two surfaces of themuscular-skeletal system. The skirt prevents materials or debris fromthe procedure from getting between the first and second supportstructures of the distractor. The skirt can be removed when a procedureis performed requiring anterior, posterior, medial, or lateral access.Alternatively, the periphery can be open and the interior space betweenthe first and second support structures can be cleaned periodically toprevent build up of debris. The distractor provides open space anterior,posterior, medially, laterally, and between the first and second supportstructures allowing the surgeon great latitude in performing surgicalprocedures in proximity to the distracted area.

In a step 1532, the muscular-skeletal system is modified in the firstrelational position. As disclosed above, modifications to themuscular-skeletal system can take many forms. Bone modification, softtissue release, implants, adding artificial or biological materials arebut a few of the modifications that can be made using the accessprovided by the distractor. Similarly, in a step 1534, themuscular-skeletal system is modified in the second relational position.In one embodiment, the distractor is not removed during sensormeasurement, movement through a range of motion, and during themodification process thereby greatly reducing the surgical time.Moreover, sensors in the distractor can provide real time measurement ofhow the modifications are affecting the distracted region. This instantfeedback and quantitative measurement allow fine adjustments to be madethat will greatly increase the consistency of orthopedic surgicalprocedures.

FIG. 16 is an exemplary method 1600 for distracting surfaces of themuscular-skeletal system in extension and in flexion in accordance withan exemplary embodiment. The method can be practiced with more or lessthan the number of steps shown and is not limited to the order shown.Steps 1602, 1604, and 1606 are respectively similar to steps 1502, 1504,and 1506 of FIG. 15 and are not described here for brevity. In a step1608, the measured parameter is changed through modification of themuscular-skeletal system. As mentioned previously, the distractor can bebroadly used on the muscular-skeletal system including but not limitedto the spinal column, knee, hip, ankle, shoulder, wrist, articulating,and non-articulating structures. In one embodiment, the measurement andthe modification of the muscular-skeletal system occurs with thedistractor in place and the leg in extension.

In a step 1610, the muscular-skeletal system is repositioned to a secondrelational position. As mentioned previously, the position of thedistracted surfaces in the second position is different from theposition of the distracted surfaces in the first position. Thedistractor remains in place during positioning to the second relationalposition. This provides the benefit of reducing surgical time and stresson the patient. In general, the support structures of the distractor andmore specifically the surfaces of the support structure allow naturalmovement of the muscular-skeletal in a normal range of motion.

In a step 1612, at least one parameter is measured by the sensor whilein the second relational position. In a step 1614, the measuredparameter is changed through modification of the muscular-skeletalsystem. The modification occurs with the muscular-skeletal system in thesecond relational position. In one embodiment, the distractor remains inplace while moving the muscular-skeletal system to the second relationalposition, during sensor measurement, and modification of themuscular-skeletal system. The surgeon or medical staff can comparemeasurement data with the muscular-skeletal system in at least twodifferent positions. Referring to a step 1628, the sensor can include atransmitter for transmitting measurement data from the sensor to aprocessing unit. In a step 1630, the measurement is displayed on adisplay. For example, the processing unit can be the microprocessor of anotebook while the display is the screen of the notebook. The data istransmitted in real time when a measurement is taken. In other words,the data is transmitted, processed, and displayed during the measurementand subsequent modification of the muscular-skeletal system in the firstrelational position. Similarly, the data is transmitted, processed, anddisplayed during the measurement and subsequent modification in thesecond relational position. The transmission of measured data can sentwirelessly using a radio frequency signal.

In a step 1522, the alignment of at least one of the first or secondrelational position is compared to a mechanical axis of themuscular-skeletal system. Typically, the muscular-skeletal system hasoptimal alignments that maximize performance of the structure. Thedistractor can be used to measure misalignment to the mechanical axis.The distractor utilizes at least one of the surface being distracted tomeasure the misalignment. The distracted surface of themuscular-skeletal system has a geometric relationship with themechanical axis. For example, the plane of the distracted surface can bea specific angle from the mechanical axis. Moreover, there can bespecific landmarks of the surface that such as a center point thatfurther identify the relationship with the mechanical axis.

In one embodiment, a plane of a portion of the surface of the distractoris co-planar with the muscular-skeletal surface it is contacting. Thisrelationship is extended to a handle of the distractor where a surfaceof the handle is co-planar to the distracted surface of themuscular-skeletal system. The handle can also extend frommuscular-skeletal system at a location corresponding to a landmark thatcorresponds to the mechanical axis. For example, it can extend centrallyor at a specific position from the distracted surface. As disclosedhereinabove, a drop rod can be attached to an opening in the handle tovisually and subjectively determine if alignment is within apredetermined range. The drop rod can also be coupled to other fixturescoupled to different areas of the muscular-skeletal system to measurealignment. Alternatively, one or more lasers can be attached to thehandle of the distractor. The lasers are directed to one or more targetsthat are located along the mechanical axis. The amount of misalignmentcan be measured by the location where the beam hits a scale on each ofthe target.

In a step 1616, the misalignment of the muscular-skeletal system ismeasured. As disclosed above, the measurement can be made using lasersand targets respectively coupled to the handle of the distractor andlocated along the mechanical axis of the muscular-skeletal system. Inone embodiment, the misalignment is referenced to at least one of thetwo surfaces being distracted by the distractor. The alignment of thesurface of the muscular-skeletal system is compared to the mechanicalaxis. In a step 1618, the muscular-skeletal system is modified to reducethe measured misalignment. As mentioned previously, there is anacceptable range for misalignment to the mechanical axis. Adjustmentsare made to reduce the error if the measurement are outside theacceptable range. In one embodiment, the corrections can be checked inreal time as the modifications are made to see that the changes to themuscular-skeletal system are moving the misalignment error to theacceptable range.

In a step 1620, the sensor measures load. In one embodiment, the twosurfaces of the muscular-skeletal system place a compressive forceacross the first and second support structures of the distractor. One ormore sensors on the first and second support structures of thedistractor can be used to measure loading and the distribution ofloading. In a step 1622, the handle of the distractor is moved away froma surgical area. In non-limiting example, the surgical area correspondsto a region where muscles, tendons, and ligaments couple the at leasttwo surfaces of the muscular-skeletal system together. The handle ismoved to a position such that modification to the soft tissue can takeplace. In a step 1624, soft tissue is cut in the surgical area to reduceloading applied by the two surfaces of the muscular-skeletal system onthe distractor. In general, the sensor can measure load, pressure, orforce. The distractor provides access for the surgeon to make cuts tothe soft tissue with the area distracted. The sensor measures in realtime allowing the surgeon to adjust the load to an optimal value. In astep 1626, the handle can be removed to further improve the anterioraccess.

FIG. 17 is an exemplary method 1700 for distracting surfaces of a kneejoint in extension and in flexion in accordance with an exemplaryembodiment. The method can be practiced with more or less than thenumber of steps shown and is not limited to the order shown. A kneejoint implant procedure of the muscular-skeletal system is used toillustrate the process of distraction. The knee joint comprises thedistal end of the femur and the proximal end of the tibia. An artificialknee joint comprises a femoral implant, an insert, and a tibal implant.The femoral implant is shaped similar to and replaces the naturalcondyles at the distal end of the femur. The insert has a bearingsurface for receiving the condyles and an inferior surface that matesand is retained by the tibial implant. In general, the artificial kneejoint mimics the natural knee joint in operation once implanted.

All the steps for preparing a knee will not be disclosed for brevity butare well known by one skilled in the art. The knee is opened by incisionto expose the distal end of the femur and the proximal end of the femur.The patella is removed or moved away from the knee joint region. Theproximal end of the tibia is prepared by cutting the bone. In oneembodiment, the proximal end of the tibia is prepared having a planarsurface. In one embodiment, the planar surface is cut perpendicular tothe mechanical axis of the leg. The distractor is then inserted into theknee joint.

The distractor has a first support structure having a superior surfacefor receiving the condyles of the femur and a second support structurehaving an inferior surface for mating to the prepared tibial surface.The shape of the support structures as disclosed herein allows naturalmovement of the leg through the range of motion with the distractor inplace. In one embodiment, two sensors are placed in the superior surfaceof the distractor for measuring load in each compartment of the knee. Ahandle is used to direct the first and second support structures intothe knee. The handle can be rotated to increase the gap of thedistractor to place the superior surface of the first support structurein contact with the condyles of the femur and the inferior surface ofthe second support structure in contact to the tibial surface. Morespecifically, each condyle will contact a surface of a correspondingsensor.

In a step 1720, the alignment of a surface of the distractor is comparedto the mechanical axis of the leg. The surface of the distractorcorresponds to a surface of the knee. In one embodiment, the surface isthe prepared surface of the tibia. Targets for leg alignment can beplaced overlying the mechanical axis of the leg. Typically one target isplaced in the ankle or foot region and a second target is placed in thehip joint region near the femoral head. The mechanical axis is astraight line from the center of the femoral head through the center ofthe knee joint to the center of the ankle. In one embodiment, handleextends from the knee joint at a point that corresponds to the center ofthe knee joint. The inferior surface of the second support structure isplanar to the tibial surface. Similarly, one or more surfaces of thehandle of the distractor is aligned to the inferior surface of thesecond support structure thereby being co-planar to the tibial surface.As disclosed hereinabove, lasers can be attached to the handle pointingtowards the ankle target and the hip target. As mentioned previously,the tibial surface is prepared to be 90 degrees from the mechanical axisof the leg. Misalignment from the mechanical axis can be measured fromwhere the beam of the laser hits the target. A correctly aligned legwill hit each target at a point representing the location of themechanical axis. In a step 1722, the measured misalignment can bereduced through modification of the muscular-skeletal system. Themodification can be to the bone, soft tissue, additional implants ormaterials (artificial and biological) that bring the femur and tibiainto alignment with the mechanical axis.

In a step 1702, the knee joint is distracted with the leg in extension.The leg is in extension when the femur and tibia are positioned having a180-degree angle between them. A handle of the distractor directs thesupport structures into the knee joint area. The handle is rotated toincrease a gap between the superior and inferior surfaces until contactis respectively made to the condyles of the femur and the surface of thetibia. The sensors in each compartment of the first support structureare in communication with an external processing unit. In oneembodiment, each condyle of the femur is in contact with a correspondingsensor surface throughout the range of motion of the leg. The surgeonpositions the distractor such that the handle corresponds to the centerof the knee joint, which aligns with the mechanical axis of the leg. Ina non-limiting example, the leg alignment to the mechanical axis can bemeasured and corrections made to reduce misalignment if outside anacceptable range.

In a step 1704, a load is measured with the leg in extension for atleast one compartment of the knee. The data is received by theprocessing unit and displayed on a display. For example, accelerometersin the sensors can show relative position of the femur to the tibia. Inone embodiment, the femur and tibia are shown on the display to providevisual information to the surgeon on positioning. The angle between thefemur and tibia can be displayed as well as alignment of the leg to themechanical axis. The sensors include a measurement device such as astrain gauge to measure load. A complete knee replacement will measureloading on both compartments of the knee.

The distractor provides quantitative data that is used by the surgeon toprepare the knee. In a non-limiting example, the knee is distracted to agap that corresponds to a combined insert and tibial implant thickness(the distal end of the femur is unprepared in the example). As is knownby one skilled in the art, inserts are available in different sizes andthicknesses. The surgeon picks a size that is best adapted for thepatient bone dimensions. The surgeon prepares the bone surfaces for anapproximate combined thickness of the implants. For illustrationpurposes a combined implant thickness of 20 millimeters could be used.Typically, several insert thicknesses are suitable based on the tibialcut and the resulting gap between the tibial surface and the condyles ofthe femur. The sensor measurements are used to select an appropriaterange and allows fine-tuning of the loading to within a very accuraterange. For the full joint replacement, the gap height of the distractor,angle between tibia/femur (180 degrees, leg in extension), the loadingon each compartment at the gap height, and the differential loadingbetween the compartments is transmitted and displayed for viewing by thesurgeon.

In a non-limiting example, the surgeon may have to increase or decreasethe gap height of the distractor depending on the sensor readings. Theincrease or decrease in gap height will correspond to an availableinsert thickness. In one embodiment, the surgeon adjusts the gap heightto measure load on the high side of a predetermined load range for eachcompartment. Selecting on a high side reading allows for fineadjustments to the final load value in a subsequent step. In general,the surgeon selects the appropriate insert size for the knee implant.

In a step 1706, the leg is moved into flexion while the distractorremains in the knee joint. As mentioned previously, the distractorprovides surfaces that allows movement of the joint through the naturalrange of motion. This provides the benefit of being able to prepare theleg for load, balance, and alignment in more than one position using asingle device. In one embodiment, the gap height of the distractorremains in the selected height for the leg in extension. Alternatively,the gap height of the distractor can be reduced while moving the leg inflexion to a final position and then readjusting the gap. In anon-limiting example, the leg is moved in flexion to a position wherethe femur and tibia form a 90-degree angle. In one embodiment, thesurgeon can move the leg while viewing femur/tibia angle on the screento get it precisely positioned.

In a step 1708, the load in at least one knee compartment is measuredwith the leg in flexion. In a non-limiting example, the gap height ofthe distractor in flexion is equal to the gap height selected by thesurgeon when the leg was in extension. The sensors communicate with theprocessing unit providing the measured load in each compartment,differential loading between compartments, and the gap height to thesurgeon with the leg in flexion. Thus, the leg can be moved fromextension to flexion with the distractor in place. The sensors canmeasure load and differential loading in different positions and gapheights that can be displayed on a screen for the surgeon to view. Thedata is also stored in memory for use.

In a step 1710, the handle of the distractor is moved from a surgicalarea with the leg in extension. As mentioned previously, the handle ofthe distractor includes a hinge to position the handle away from asurgical area or can be removed to have anterior access to thedistracted area. The surgical area corresponds to the muscle andligaments coupling the femur to the tibia. The muscle and ligaments inthe surgical area are located laterally and medially around the kneejoint. A space is typically opened between the first and second supportstructures when the knee joint is distracted. Thus, the distractorenables soft tissue release by providing access from multiple vantagepoints to the muscle and ligaments with the device in place.

In a step 1712, the load in at least one compartment of the knee isreduced with the leg in extension. The handle is positioned to allowanterior and peripheral access to the soft tissue for incision. Thesurgeon can also place a scalpel between the first and second supportstructures for an interior or peripheral cut to the soft tissue ifneeded. In a non-limiting example, the soft tissue release can beperformed when the leg is in extension after the loading is measured andthe gap adjusted to a height selected by the surgeon. The soft tissuerelease can be performed on either the lateral or the medial sides ofthe knee or on both sides. In one embodiment, the soft tissue release isperformed to bring each compartment loading within a predetermineloading range. The sensor data is transmitted, processed, and displayedin real time allowing the surgeon to view the actual measured effect ofeach cut on the loading in both compartments.

Referring to a step 1714, the load, force, or pressure in both kneecompartments are measured with the leg in extension. In a step 1716, themeasured load in each compartment is compared and a differential loadingis calculated. In a step 1718, the differential loading between the twoknee compartments is reduced using soft tissue release with thedistractor in the knee joint. The surgeon can fine-tune the leg inextension to balance the loading between compartments with thedistractor in place. In one embodiment, the surgeon can reduce themeasured load on the side reading the highest value and bring thedifferential loading down within a predetermined differential loadingrange. In the example, the absolute loading measured in each compartmenthas also been reduced within a predetermined acceptable load range. Aspreviously disclosed, the gap generated by the distractor corresponds toan available thickness insert of the artificial knee joint. The displaycan provide indicators to the surgeon when the measured load or thedifferential load is within their respective appropriate ranges.

In a step 1722, the handle of the distractor is moved from a surgicalarea with the leg in flexion. As mentioned previously, the leg ispositioned with the femur and tibia at a right angle. In a step 1724,the load in at least one compartment of the knee is reduced with the legin flexion. The handle is positioned to allow anterior and peripheralaccess to the soft tissue for incision. The surgeon can also place ascalpel between the first and second support structures for an interioror peripheral cut to the soft tissue if needed. In a non-limitingexample, the soft tissue release can be performed when the leg is inextension after the loading is measured and the gap adjusted to a heightselected by the surgeon. The soft tissue release can be performed oneither the lateral or the medial sides of the knee or on both sides. Inone embodiment, the soft tissue release is performed to bring eachcompartment loading within a predetermine loading range. The sensor datais transmitted, processed, and displayed in real time allowing thesurgeon to view the actual measured effect of each cut on the loading inboth compartments with the leg in flexion.

In a step 1726, the load, force, or pressure in both knee compartmentsare measured with the leg in flexion. In a step 1728, the measured loadin each compartment is compared and a differential loading iscalculated. In a step 1730, the differential loading between the twoknee compartments with the leg in flexion is reduced using soft tissuerelease with the distractor in the knee joint. The surgeon can fine-tunethe leg in extension to balance the loading between compartments withthe distractor in place. In one embodiment, the surgeon can reduce themeasured load on the side reading the highest value and bring thedifferential loading down within a predetermined differential loadingrange. In the example, the absolute loading measured in each compartmenthas also been reduced within a predetermined acceptable load range. Aspreviously disclosed, the gap generated by the distractor corresponds toan available thickness insert of the artificial knee joint. In thenon-limiting example, the gap created by the distractor in extension andflexion is the same. The display can provide indicators to the surgeonwhen the measured load or the differential load is within theirrespective appropriate ranges when the leg is in flexion. The surgeoncan take further measurements on load and balance by moving the leg indifferent positions of flexion and recording the values. Furtheradjustments could be made to refine load and balance in these otherflexion positions with the distractor in place.

FIG. 18 is an exemplary method 1800 to place the muscular-skeletalsystem in a fixed position for bone shaping in accordance with anexemplary embodiment. The method can be practiced with more or less thanthe number of steps shown and is not limited to the order shown. Aspacer is a device that as it names implies spaces two surfaces apartfrom each other. A spacer can have a fixed height or can be variable. Inone embodiment, a spacer has an inferior surface and a superior surfacefor coupling to surfaces of the muscular-skeletal system. A spacer witha fixed height is also known as a spacer block in the orthopedic field.A spacer having variable height is known as a distractor.

In a step 1802, a spacer is placed between two surfaces of themuscular-skeletal system. The spacer separates the two surfaces of themuscular-skeletal system. In one embodiment, the spacer is placedbetween two bones. The superior surface of the spacer couples to asurface of a first bone and the inferior surface couples to a surface ofa second bone. There can be other material or components between thesuperior and inferior surface of spacer and the bone surfaces. Thus, thespacer separates the first and second bone surfaces by at least theheight of the spacer.

In a step 1804, a cutting block is coupled to an exposed portion of oneof the two bone surfaces. A cutting block is a template for shaping abone surface. It is typically fastened to a bone surface and can haveslots and openings for guiding surgical tools such as a bone saw. In oneembodiment, a cutting block is used to shape a bone end for receivingone or more artificial implant components or material. In many cases,the position of the cutting block is not arbitrary but has to haveprecision alignment. For example, when performing a joint replacement,the cutting block has to be positioned having one or more alignments tothe muscular-skeletal system. Misalignment can cause joint failure andpremature wear. An illustration of alignment will be disclosed in moredetail by example hereinbelow.

In a step 1806, the spacer is coupled to the cutting block to rigidlyposition the two surfaces in a predetermined position. Cutting blocksare typically designed to be used to shape the bones with the twosurfaces and more specifically the bones having the surfaces in aspecific position and alignment. In one embodiment, the spacer is fixedin position to at least one of the bone surfaces. The spacer can beunder compressive force due to muscle, ligaments and tendons couplingthe first and second bones together. Alternatively, the spacer can betemporarily attached to one of the surfaces. For example, a surgicalscrew or pin can be used to fix the spacer position. If the spacer is adistractor, the compressive force can be adjusted by increasing ordecreasing the height between the superior and inferior surfaces. Thespacer can allow the two bones to move in relation to one another in anatural range of motion without movement of the device to the bonesurface. The spacer and the cutting block are couple together to preventmovement of the first bone, second bone, bone surfaces, and cuttingblock. Coupling the spacer to the cutting block stabilizes the cuttingblock and keeps the first and second bones in a fixed relation to oneanother while the bone surface is shaped.

In a step 1810, the misalignment of at least one of the surfaces ismeasured in relation to a mechanical axis of the muscular-skeletalsystem. In general, alignment of the muscular-skeletal system iscritical to obtain optimal performance and longevity. In fact, manyproblems that end up requiring surgery are due to misalignment ordeformity that causes premature wear or damage to the muscular-skeletalsystem that can directly or indirectly result in a disability or healthproblem. Implanted devices and artificial joints follow similarconstraints from a geometric standpoint since many mimic the naturaldevice. Thus, the surgeon needs affirmation that the alignment of themuscular-skeletal system while modifying bone and soft tissue to receiveimplanted components. Typically, at least one of the bone surfaces has arelationship with a mechanical axis of the muscular-skeletal system. Themechanical axis is an optimal alignment of the bone or bone surface toanother portion of muscular-skeletal system. In a non-limiting example,the bone surfaces and the thus the bones having the bone surfaces havean optimal alignment. This optimal alignment is known as the mechanicalaxis.

In one embodiment, a surface or feature of the handle corresponds to asurface of the muscular-skeletal system. This relationship can be usedto compare the orientation of the surface or feature to a mechanicalaxis. The superior or inferior surface of the spacer couples to thesurface (or reference surface). The surface of the spacer is shapedsimilarly to the reference surface. For example, if the referencesurface of the muscular-skeletal system is planar, the spacer surface isalso made planar and has a relational position of being co-planar orparallel to the reference surface. A feature or the surface of a featuresuch as an opening, recess, mounting structure can have a specificorientation to the reference surface. For example, an opening can havean orientation that is perpendicular to the reference surface. Thus, theopening will extend in a direction approximately perpendicular to themuscular-skeletal reference surface on which the spacer is coupled. Thehandle can have one or more surfaces or features made to have specificrelational positions to one or both of the spacer surfaces. For example,at least one surface of the handle can be made co-planar to the spacersurface corresponding to the muscular-skeletal reference surface. Thesurface on the handle can be used to create features that have specificpositional relationships to the plane of the muscular-skeletal referencesurface to aid in determining misalignment. Measurement of misalignmentwill be discussed in more detail hereinbelow.

As disclosed hereinabove, the mechanical axis can be defined by placingtargets overlying the patient that align to the axis or to referencepoints of the body. For illustrative purposes, the leg in extension willbe used to describe a mechanical axis of the muscular-skeletal systemfor a knee joint replacement. The mechanical axis of the leg inextension is a straight line from the center of the femoral head, to thecenter of the knee joint, and continuing to the center of the ankle. Thetargets are placed above the mechanical axis and typically near theankle region and the center of the femoral head. In one embodiment, thehandle is aligned with the center of the knee joint and extendsvertically from the knee. In a non-limiting example, a feature such as acenter of at least one opening or a recess in the handle isgeometrically aligned to the knee center and corresponds to a point onthe mechanical axis. The mechanical axis corresponds to a straight linefrom a point on the ankle target (e.g. ankle center), to a point on thehandle, and extending to a point on hip target (e.g. center of femoralhead). Extending a plane of the mechanical axis vertically (e.g. 90degrees to the horizontal plane) with the leg in extension wouldintersect the center of the feature on the handle. In the example, theproximal end of the tibia is prepared by the surgeon as a flat surface.Ideally, the mechanical axis of the intersects the plane of the preparedtibial surface at a right angle. In a non-limiting example, lasers arecoupled openings or recesses in the handle of the spacer. The laserspoint towards the ankle target and the hip target. The lasers arepointed at a 90-degree angle from the plane of the prepared bonesurface. Thus, misalignment can be measured from the targets as thedifference angle between the point where beams hit the target and theidentified point on each target corresponding to the mechanical axis.

In a step 1812 the muscular-skeletal system is modified to reduce themisalignment within a predetermined range. Once the misalignment ismeasured the surgeon can determine if modification to themuscular-skeletal system is required and what type of modification issuitable to reduce the error. In general, keeping the misalignmentwithin a predetermined range will improve consistency of the surgery.Implant manufacturers can use the surgical data to determine thesensitivity of misalignment to rework, patient problems, and implantlongevity.

In a step 1814 the spacer is aligned between the two surfaces where ahandle of the spacer intersects the mechanical axis. Typically, thespacer alignment occurs before the misalignment to the mechanical axisis measured. As disclosed above, the spacer is part of an alignmentsystem. The spacer has a predetermined position or alignment between thefirst and second bone surfaces and more specifically on the referencebone surface. In one embodiment, the handle extends from the spacer andintersects the mechanical axis. In the non-limiting example, the spaceris placed on the prepared tibial surface such that a superior surface ofthe spacer mates with the condyles of the femur. Moreover, the handleextends centrally from the spacer with the leg in extensioncorresponding to the center of the knee joint (e.g. a point on themechanical axis).

In a step 1816, a rod is coupled to the handle. The handle has a knownrelational positioning to the mechanical axis within the predeterminedrange as described hereinabove. In one embodiment, the rod fits into anopening in the handle. The rod can be fastened to the handle. Forexample, portions of the rod and the opening in the rod can be threaded.Alternatively, the rod can be held in place by a powerful magnet, clamp,screw, or other means. In general, the rod is rigid and projects thepositional relationship of the handle (e.g. the bone reference surface).In the knee example, the tibia and femur are placed in flexion. Morespecifically, the tibia and femur are positioned having a 90-degreeangle between the bones. The cutting block is on the exposed portion ofthe distal end of the femur to be shaped. Thus, the entire distal end ofthe femur is not shaped in this position.

In a step 1818, the rod is coupled to the cutting block. The rod is thencoupled to both the handle and the cutting block. In one embodiment, thecutting block has a channel approximately the same diameter as the rod.The rod is placed in the channel of the cutting block. The rod fixes theposition of the spacer and the cutting block. As mentioned previously,the spacer and the handle is within a predetermine range of themechanical axis. In a non-limiting example, the rod extends along themechanical axis. Placing the rod into the channel aligns the cuttingblock to the mechanical axis. The rod fixes the relational position ofthe first bone surface to the second bone surface. In the embodiment,the femur and tibia are aligned to the mechanical axis and positionedperpendicular to each other.

In a step 1820, the gap of the spacer is changed. In one embodiment, thespacer is a dynamic distractor. The dynamic distractor includes sensorsto measure loading. As the gap of the distractor is increased the firstand second bone surfaces apply a compressive force on the spacer. Themuscle, ligaments, and tendons couple the two bones holding themtogether under tension. The gap can be adjusted to be within apredetermined measured loading range (at the distracted gap height).

In a step 1822, the bone surface is shaped. The cutting block is used asa template to direct a saw blade to shape the bone. With the rod rigidlyholding the bone surfaces in place the cutting block is stabilized andin alignment with the mechanical axis. In the knee example, the exposedportion distal end of the femur can be shaped with the leg in flexion.The shaped surface can receive an implant that will be aligned correctlyto the mechanical axis as well as the femur and tibia surfaces.

FIG. 19 is an exemplary method 1900 of measuring the muscular-skeletalsystem in accordance with an exemplary embodiment. The method can bepracticed with more or less than the number of steps shown and is notlimited to the order shown. In a non-limiting example a spacer is adevice that separates two surfaces of the muscular-skeletal system. Thespacer has an inferior surface and a superior surface that contact thetwo surfaces. The spacer can have a fixed height or can have a variableheight. A fixed height spacer is commonly called a spacer block. Thevariable height spacer is known as a distractor. The use of spacerdisclosed herein includes the spacer block and the distractor. In oneembodiment, a handle extends from the spacer and typically residesoutside or beyond the two surface regions being distracted. The handleis used to direct the spacer between the two surfaces. In oneembodiment, the handle operatively couples to a lift mechanism of thedistractor to increase and decrease a gap between the superior andinferior surfaces of the spacer. The spacer and handle is part of asystem to measure alignment of the muscular-skeletal system. In oneembodiment, at least one of the surfaces of the muscular-skeletal systemthat contacts the spacer has an optimal alignment to a mechanical axisof the muscular-skeletal system. The system measures the surface tomechanical axis alignment. In a non-limiting example, the surface can becorrected by a surgeon when the surface is misaligned to the mechanicalaxis outside a predetermined range.

A surface or feature of the handle has a relational position to the(reference or alignment) surface of the two surfaces that the spacercontacts. In one embodiment, the reference surface of themuscular-skeletal system is a planar surface. The surface of the spacercontacting the reference surface of is also planar and thus has therelational position of being planar or co-planar when coupled thereto.Similarly, the handle is attached or coupled to the spacer block ordistractor having a relational position to the surface of the spacerthat contacts the reference surface. Typically, the relational positionof the surface or feature on the handle is co-planar or perpendicular tothe surface of the spacer.

The two surfaces of the muscular-skeletal system are typicallypositioned in predetermined relation before measuring misalignment tothe mechanical axis. The predetermined relation typically corresponds toa natural position of the muscular-skeletal system. For example, acommon position is the tibia positioned 180 degrees from the femur,which is commonly known as a leg in extension. In this example, thereference surface is a proximal tibial surface of the tibia. In oneembodiment, the proximal tibial surface is a planar surface prepared bythe surgeon. Ideally, the tibial surface is formed perpendicular to themechanical axis with the leg in extension. A measurement of the tibialsurface to the mechanical axis is performed to verify that it is withina predetermined range or specification. Similarly, a measurement isoften taken with the muscular-skeletal system in a second predeterminedrelation. The second predetermined relation is typically at a differentpoint in the range of natural motion. For example, the leg in extensionwith the tibia positioned 90 degrees from the femur. One or more sensorssuch as accelerometers can be use to measure the relational positioningof the two surfaces of the muscular-skeletal system.

In one embodiment, a feature such as an opening or cavity is formed inthe handle. The opening or cavity has a relational positioning to thereference surface when the spacer block or distractor is placed betweenthe two surfaces of the muscular-skeletal system. In a non-limitingexample to illustrate the relational positioning, the opening or cavityis perpendicular to the plane of the reference surface. In the examplewhere the mechanical axis is ideally perpendicular to the referencesurface a rod is placed in the opening or cavity. The rod is directedperpendicular to the plane of the reference surface. A comparison of thedirection of the rod to the mechanical axis yields misalignment of thereference surface to the ideal. The surgeon can use the rod withlandmarks that identify the mechanical axis to make a visualdetermination of alignment. Alternatively, the rod can be used tomeasure an angle difference between the mechanical axis and the actualmuscular-skeletal alignment. Furthermore, the rod can include one ormore sensors for measuring a parameter of the muscular-skeletal systemincluding alignment.

In another embodiment, targets are placed on the muscular-skeletalsystem aligned with the mechanical axis. An axis point or axis line onthe target aligns with the mechanical axis. A laser is placed in theopening or cavity on the handle. In a non-limiting example, the centerof the opening or cavity corresponds to an axis point on the mechanicalaxis. The mechanical axis is a straight line between the center of theopening and one or more targets. The beam of the laser is directed tothe target. Using the example above, the beam is directed perpendicularto the plane of the reference surface to the target. The position wherethe beam hits the target corresponds to misalignment of the referencesurface to the mechanical axis. The misalignment results in the beamhitting the target on either side of the axis point or line. In asimilar fashion the location of the beam on the target could also beused to determine if the reference surface has a slope by viewing wherethe beam hits the target in an opposite plane. For example, if themisalignment measurement is on a horizontal plane relative to the axispoint, a slope of the reference surface can correspond to the beamlocation on a vertical plane or above/below the axis point.

In a step 1902, two surfaces of the muscular-skeletal system aredistracted with a spacer. The gap between the two surfaces can be variedwith the distractor. In a step 1904, an alignment aid is coupled to ahandle of the distractor. The misalignment of a surface (e.g. referencesurface) of the two surfaces to a mechanical axis is measured with analignment aid that is coupled to a handle of the distractor. Thealignment aid is coupled to a surface or feature of the handle of thedistractor that has a relational position to the reference surface. Inone embodiment, an alignment aid can be a laser and at least one target.Referring to a step 1926, at least one laser is coupled to the handle ofthe distractor. In one embodiment, the at least one laser is coupled toa feature such as an opening or cavity. In a step 1928, at least onetarget is coupled to the muscular-skeletal system. In general, the atleast one target can be placed overlying the muscular-skeletal systemsuch in a location corresponding to an axis point of the mechanicalaxis. An axis point on the target aligns to the mechanical axis. Thebeam from the laser hits the target. The point where the beam hits iscompared to the axis point of the target that corresponds to themechanical axis. The target can have a scale that measures misalignmentof the surface to the mechanical axis. As disclosed above, the directionof the laser corresponds to the surface of the muscular-skeletal system.

In a step 1906, the two surfaces of the muscular-skeletal system areplaced in a first position. The misalignment of the surface to themechanical axis is measured. In a step 1908, the misalignment iscorrected if the measurement is outside a predetermined range. Ingeneral, data generated by this system can yield significant informationon how misalignment affects the muscular-skeletal system. The data canbe used to further identify the optimal predetermined range thatminimizes the effect of misalignment and consistently produces apositive outcome. In a step 1910, the gap or the space between theinferior and superior surfaces of the spacer is measured. In a step1912, a force, pressure, or load applied by the two surfaces of themuscular-skeletal system on the distractor is measured. One or moresensors can be placed in the superior or inferior surfaces to measure aparameter such as but not limited to force, pressure, or load. The twosurfaces of the muscular-skeletal system apply pressure or force to thesuperior and inferior surfaces of the spacer and more specifically on atleast one sensor on either surface of the distractor. The measurementsof steps 1908, 1910, and 1912 are completed with the muscular-skeletalsystem in the first position. As mentioned above, the first position istypically a geometrically significant position of the muscular-skeletalsystem that allows comparison to the mechanical axis. The measurementdata is transmitted to a processing unit for viewing on a display andfor long-term storage. The system allows for real time measurement ifand when the muscular-skeletal system is modified with the distractor inplace.

The following measurements steps are similar to the measurements in thefirst position described above. In a step 1916, the two surfaces of themuscular-skeletal system are placed in a second position. Themisalignment of the surface to the mechanical axis can be measured inthe second position to verify alignment. In a step 1918, themisalignment is corrected in if the measurement is outside apredetermined range. In a step 1920, the gap or the space between theinferior and superior surfaces of the spacer is measured. In a step1922, a force, pressure, or load applied by the two surfaces of themuscular-skeletal system on the distractor is measured. The measurementsof steps 1918, 1920, and 1922 are completed with the muscular-skeletalsystem in the second position. As mentioned above, the second positionis also a geometrically significant position of the muscular-skeletalsystem that allows comparison to the mechanical axis. The measurementdata is transmitted to the processing unit. The system allows for realtime measurement in the second position.

FIG. 20 is an exemplary method 2000 of a disposable orthopedic system inaccordance with an exemplary embodiment. The method can be practicedwith more or less than the number of steps shown and is not limited tothe order shown. In a step 2002, at least one parameter of themuscular-skeletal system is measured with a sensor. As disclosedhereinabove, the sensor provides accurate measurements of parameterssuch as distance, weight, strain, load, pressure, force wear, vibration,viscosity, and density. In one embodiment, the sensor is a disposablesensor. In a non-limiting example, the disposable sensor is adapted toan orthopedic device such as a tool or implantable component. The sensoris sterilized and placed in a package that maintains sterility. Thesensor is typically contaminated with biological material when used tomeasure the muscular-skeletal system during a surgical procedure. In astep 2004, the sensor is disposed of after use. The sensor is disposedof as biological waste if contaminated by biological material during theprocedure. Packaging of a single use device greatly reduces cost, as thehousing does not have to withstand repeated cleanings. Moreover, iteliminates the cost of a sterilization process. In a non-limitingexample, the sensor is used in orthopedic surgery and more specificallyto provide intra-operative measurement during joint implant surgery.

In a step 2022, the sensor is powered. In one embodiment, the sensor isnot powered until it is used. The sensor can have a temporary powersource that powers the device for a procedure. A charger can be providedto charge the unit up prior to use. The power source can be internal tothe sensor to prevent issues with sterility. The temporary power sourcecan sustain the device for a predetermined period of time that issufficient for the procedure but prevents reuse of the device. Thesensor is in communication with a processing unit. In one embodiment,the processing unit is located external to the sensor. In the surgicalexample, the processing unit is located outside of the immediatesurgical area. For illustration purposes, the processing unit is amicroprocessor of a notebook computer.

In a step 2024, patient information is inputted to the processing unit.The patient information can input through a variety of methods. Forexample, the information can be typed in, scanned in, downloaded viaradio frequency tag, or verbally transmitted, recorded, and converted.The patient information can be displayed on a screen of the notebookcomputer. The patient information can include personal, medical, andspecific information related to the procedure.

In a step 2026, a reader is coupled to the processing unit. The readercan be wired or wireless. In a step 2028, the reader is used to scan ininformation pertaining to the procedure. In one embodiment, the readeris used to scan in components of the system such as the sensors,alignment aids, implant components, and other devices prior to use. In anon-limiting example, the information can be used for identification ofthe specific components (e.g. serial numbers) used during the procedure.The information can be used for billing, patient records, long termmonitoring of components, and component recall.

In a step 2006, the sensor is placed between two surfaces of themuscular-skeletal system. The sensor measures a parameter in proximityto the surfaces of the muscular-skeletal system. In one embodiment, thetwo surfaces are exposed by incision. For example, the sensor has asmall form factor allowing it to be placed in or on a spacer. A spacerseparates the two surfaces of muscular-skeletal system. Examples of aspacer are a spacer block or a distractor. In a non-limiting example, ajoint of the muscular-skeletal system is exposed. One or more of thejoint surfaces can be shaped or prepared by the surgeon. The spacerblock or distractor is placed between the joint surfaces of themuscular-skeletal system. The sensor can have an exposed surface thatwill contact at least one of the two surfaces.

In a step 2008, a load, force, or pressure applied by the two surfaceson the sensor is measured. For example, the spacer block or distractordistracts the joint of the muscular-skeletal system. A measurement ofthe load, force, or pressure is measured by the sensor for a spacing orgap. The gap is the distance between the two surfaces of themuscular-skeletal system. In a step 2016, a gap can be varied betweenthe two surfaces of the muscular-skeletal system with the spacer inplace. In one embodiment, the gap is varied by a distractor between thetwo surfaces. The distractor includes a lift mechanism that can increaseor decrease a gap between the two surfaces. The sensor can measure oneor more parameters at each gap height.

In a step 2010, the sensor is placed in a cavity of a surface of aspacer. In general, a spacer has a superior and inferior surface. Thesuperior and inferior surfaces are placed between the two surfaces ofthe muscular-skeletal system. The superior and inferior surfaces come incontact with the two surfaces of the muscular-skeletal system underdistraction. In one embodiment, one of the inferior or superior surfacesof the spacer have a cavity or recess for receiving the sensor. Thesensor is placed in the cavity exposing a surface of the sensor. Thesurface of the sensor can be planar with the surface of the spacer. Asdisclosed above, the spacer can be placed between the two surfaces ofthe muscular-skeletal system such that the surface of the sensor is inproximity or in contact with one or both of the surfaces.

In a step 2012, the sensor is removed from the cavity or recess. Thesensor can have a feature that simplifies removal from the superior orinferior surface of a device. For example, the sensor can have a tab,indentation, or surface feature that allows removal by hand or with atool. Alternatively, the device in which the sensor is placed can have amechanism to push the sensor out of the recess. In a step 2014, thesensor is disposed of after being removed from the cavity or recess.

In a step 2018, an alignment of a surface to a mechanical axis ismeasured with an alignment aid. In general, at least one of the twosurfaces of the muscular-skeletal system has an alignment with amechanical axis of the muscular-skeletal system. The alignment to themechanical axis needs to be preserved or corrected during the procedure.Similar to the sensor above, components of the alignment aid aredesigned for a single use. In one embodiment, the mechanical axis isidentified. Similarly, the surface of the muscular-skeletal system iscompared to the mechanical axis. The difference between the mechanicalaxis and surface of the muscular-skeletal system is a measure of themisalignment. Adjustments to the muscular-skeletal system can beperformed to reduce misalignment within a predetermined range. In a step2020, at least one component of the alignment aid is disposed of afterthe procedure is completed.

FIG. 21 is an exemplary method 2100 of a disposable orthopedic system inaccordance with an exemplary embodiment. The method can be practicedwith more or less than the number of steps shown and is not limited tothe order shown. In a step 2102, an alignment of a surface to amechanical axis is measured with an alignment aid. In general, amechanical axis is identified by the alignment aid. The mechanical axisis then compared to an alignment of one or more surfaces or structuresof the muscular-skeletal system. Ideally, the difference or misalignmentof the surfaces or structures to the mechanical axis should be within apredetermined range that places the surfaces or structures in an optimalmuscular-skeletal kinematic setting.

In a non-limiting example, targets and more specifically a point on eachtarget correspond to points on the mechanical axis. The targets arecoupled to the muscular-skeletal system in proximity to the surfaces ofthe muscular-skeletal system. The surfaces can be part of structures ofthe muscular-skeletal system such as bones, muscles, ligament, tendons,and cartilage. The structures corresponding to the surfaces can have arelational positioning in 3D space that relate to the position of thesurfaces to each other. In one embodiment, the surface is between thetargets. Alternatively, the targets can be placed having an unobstructedpath to the surface that allows measurement. The targets can also alignhaving a more complex geometry to represent the mechanical axis. One ormore lasers are mounted at a height where a beam from a laser will hitthe target unless grossly misaligned. The laser is mounted having apredetermined positional relationship to the plane of the surface. Forexample, the laser is directed 90 from the plane of the surfacecorresponding to a direction of the mechanical axis. The targets canhave calibration markings to indicate a measure of misalignment. Thebeam from the laser will hit the point on each target if the plane ofthe surface is aligned correctly to the mechanical axis. Conversely, thedistance from the point on each target is representative of themisalignment. The calibration marking where the beam hits represents themisalignment. Adjustments to the muscular-skeletal system can beperformed to reduce misalignment within a predetermined range. In a step2104, at least one component of the alignment aid is disposed of afterthe procedure is completed. For example, the targets or lasers that arewithin the surgical field.

In one embodiment, the alignment is performed with a distractor betweenthe two surfaces of the muscular-skeletal system. The distractorseparates the surfaces of the muscular-skeletal system. In a step 2122,the two surfaces of the muscular-skeletal system are distracted whenmeasuring alignment. The distractor can vary the gap between the twosurfaces of the muscular-skeletal system allowing measurements to betaken with varying gap heights.

In a step 2106, at least one parameter of the muscular-skeletal systemis measured with a sensor. As disclosed hereinabove, the sensor providesaccurate measurements of parameters such as distance, weight, strain,load, pressure, force wear, vibration, viscosity, and density. In oneembodiment, the sensor is a disposable sensor. In a step 2108, thesensor is disposed of after use. The sensor is disposed of as biologicalwaste if contaminated by biological material during the procedure. Adisposable sensor provides data for providing quantitative data on theprocedure without the large capital expenditure required for traditionalmeasuring equipment.

In general, data is collected relevant to the procedure. For example,patient information and component information can be collected andstored in an electronic format prior to the procedure being performed.Component information can relate to products used in the procedure suchas serial number, date of production, model number, and other relateddata that identifies the product. In a step 2014, the sensor is powered.In one embodiment, the sensor is not powered until it is used. Onceenabled, the sensor can establish communication with a processing unit.The processing unit can be a collection point for information. Theprocessing unit is coupled to memory that can store information locallyor send the information to a database. Similarly, the sensor can haveinformation pertaining to the sensor product stored in memory. Thesensor can send this information to the processing unit as part of theinformation collection process. In a step 2116, patient information isinput and provided to the processing unit. The patient information canbe input through a variety of methods. For example, the information canbe typed in, scanned in, downloaded via radio frequency tag, or verballytransmitted, recorded, and converted. The patient and componentinformation can be displayed on a screen coupled to the processing unitfor use by the surgeon or other healthcare providers. The patientinformation can be encrypted to prevent access by unauthorized people.The patient information can include personal, medical, and specificinformation related to the procedure. In a step 2118, a reader iscoupled to the processing unit. The reader can be wired or wireless. Ina step 2120, the reader is used to scan in information pertaining to theprocedure. In one embodiment, the reader is an alternate approach ofdata collection of components and information. The reader is used toscan and input information displayed on components or packaging ofcomponents. The information can be used for billing, patient records,long term monitoring of components, and component recall.

In a step 2110, data measured by the sensor is transmitted to theprocessing unit. The system dynamically measures a parameter of themuscular skeletal system. For example, the system can measure theparameter when the muscular-skeletal system is placed in differentpositions whereby the position of the surfaces also differs. Anotherexample is modification of the muscular-skeletal system. The sensorreading adjusts as the modification of the muscular-skeletal systemchanges the parameter being measured. In a step 2112, the data isdisplayed in real time on the display. In one embodiment, the sensortransmits data as soon as a measurement is taken. The data is thenprocessed by the processing unit and displayed in a format that aids thesurgeon or healthcare worker. Thus, any change in the parameter isstored and displayed while the sensor is enabled.

In summary, the invention describes a system to define the joint gap,bone preparation, alignment, load, and balance by measurement.Furthermore the surgeon obtains the information in real time from thesystem while soft tissue release and alignment is being performed. Thegraphic user interface can be in the device itself or integrated with aprocessing unit and display in the operating room. The sensors can beincorporated into tools and equipment for measuring themuscular-skeletal system pre-operatively, intra-operatively,post-operatively, and long term. The sensors or sensor system is incommunication with a data registry and repository to generatestatistically significant data that can be used as clinical evidence.The data repository and registry further includes information used inevidentiary based orthopedic medicine. This invention while intended foruse in the medical field and more specifically orthopedics uses a kneeapplication to illustrate principles of the system and method forillustrative purposes only and can be similarly adapted for the hip,shoulder, ankle, spine, as well as to measure other parameters of abiological system.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

1. An orthopedic system comprising: a device coupled to amuscular-skeletal system; a surface or feature on the device having arelational position to at least one of surface of the muscular-skeletalsystem where the surface or feature is used to determine alignment witha mechanical axis of the muscular-skeletal system.
 2. The system ofclaim 1 where the device includes: a spacer having a superior surfaceand an inferior surface to distract two surfaces of themuscular-skeletal system; a handle coupled to the spacer where thehandle includes the surface or feature; and an alignment aid coupled tosurface or feature of the handle.
 3. The system of claim 2 where thealignment aid coupled to the surface or feature of the handle is used todetermine misalignment between the at least one surface of themuscular-skeletal system and a mechanical axis of the muscular-skeletalsystem.
 4. The system of claim 3 further including a sensor coupled tothe spacer for determining a relative position of at least two bones ofthe muscular-skeletal system.
 5. The system of claim 1 where thealignment aid comprises a rod, where the feature is an opening orcavity, where the rod is directed perpendicular to a plane of the atleast one surface of the muscular-skeletal system.
 6. The system ofclaim 5 where the rod corresponds to an alignment of the at least onesurface to the mechanical axis.
 7. The system of claim 5 where the rodincludes at least one sensor to measure a parameter of themuscular-skeletal system.
 8. The system of claim 2 where the alignmenttool comprises: at least one laser coupled to the surface or feature ofthe handle; and at least one target coupled to the muscular-skeletalsystem where the at least one target is positioned to be in alignmentwith the mechanical axis.
 9. The system of claim 8 where the laser isdirected perpendicular to a plane of the at least one surface of themuscular-skeletal system.
 10. The system of claim 2 further including atleast one sensor overlying a superior or inferior surface of the spacerto measure at least one parameter of the muscular-skeletal system. 11.The system of claim 10 where a spacing between the superior surface andthe inferior surface is adjustable in height and where the handle can bemoved away from a surgical area.
 12. A method of measuring themuscular-skeletal system comprising the steps of: distracting twosurfaces of the muscular-skeletal system with a spacer; and measuringmisalignment of a surface of the two surfaces to a mechanical axis withan alignment aid coupled to a handle of the spacer block where thealignment aid is coupled to a surface or feature on the handle that hasa relational position to the surface.
 13. The method of claim 12 furtherincluding the steps of: placing the two surfaces of themuscular-skeletal system in a first position; correcting misalignment ofthe surface if outside a predetermined range; measuring a gap betweenthe two surfaces; measuring a force applied by the two surfaces on thespacer; and transmitting measurement data to a processing unit.
 14. Themethod of claim 12 further including the steps of: placing the twosurfaces of the muscular-skeletal system in a second position; checkingalignment of the surface to the mechanical axis in the second position;measuring a gap between the two surface in the second position;measuring a force applied by the two surfaces on the distractor in thesecond position; and transmitting measurement data to the processingunit.
 15. The method of claim 12 where the step of measuringmisalignment further includes the steps of: coupling at least one laserto the handle; and coupling at least one target to the muscular-skeletalsystem where a location of the beam hitting the target corresponds tothe misalignment of the surface to the mechanical axis.
 16. Anorthopedic system comprising: a dynamic distractor having a superiorsurface and an inferior surface to variably distract at least twosurfaces of the muscular-skeletal system where either the superior orinferior surface includes a sensor for measuring at least one parameterof the muscular-skeletal system; and a handle coupled to the distractorwhere the handle has at least one feature having a relational positionto a surface of the at least two surfaces of the muscular-skeletalsystem to aid in determining misalignment to a mechanical axis of themuscular-skeletal system.
 17. The system of claim 16 where therelational position of the feature is perpendicular to a plane of the atleast one surface of the muscular-skeletal system.
 18. The system ofclaim 17 where a center of the feature is aligned to the mechanicalaxis.
 19. The system of claim 16 where the feature is an opening or acavity in the handle, where a rod is coupled to the feature to indicatea direction perpendicular to the at least one surface of themuscular-skeletal system, and where the direction of the rod is comparedto the mechanical axis to determine misalignment.
 20. The system ofclaim 16 further including: at least one laser coupled to the feature ofthe handle; and at least one target coupled to the muscular-skeletalsystem where the at least one target is positioned to be in alignmentwith the mechanical axis.